Exam 4 Flashcards
(295 cards)
1
Q
(KEYTRUDA) Pembrolizumab (Merck 2017)
A
- Novel therapeutic Ab that inhibits PD-L1 and allows T-cells to kill cancer cell
- PD-L1 is normally expressed to inhibit autoimmunity…
- Some tumors (Ex. melanoma) overexpress PD-L1 to suppress T-cells.
2
Q
A Number of Proteins Associate With? examples?
A
- microtubule (MAPs)
- Ex. MAP2, MAP4, Tau
- Motors: Kinesin, Dynein
3
Q
A Variety of Proteins Participate in
A
in Docking and Fusion of exocytic vesicles with target membrane.
4
Q
actin and tubulin are found in
A
all eukaryotes
5
Q
Adaptor proteins
A
promote coat assembly, and help recruit specific receptor cargo.
6
Q
Address/tethering proteins
A
(Ex. Rabs) help initiate interaction
7
Q
Adenylate Cyclase
A
- is a Major Target for Many G-protein Linked Receptors.
- Produces cAMP (second messenger)- which stimulates Protein Kinase A (PKA)
- Gs/olf = stimulate adenylate cyclase
- Gi = inhibits adenylate cyclase
8
Q
All mRNA’s Initially Associate With
A
cytosolic ribosomes (translation always begins in the cytoplasm but may end in the cytoplasm or ER)
9
Q
All mutations lead to
A
either an altered protein or protein level.
10
Q
alpha I
A
- “Inhibit” Adenylyl cyclase
- Ex. 2-adrenergic, opiate, Dopamine-2
11
Q
alpha olf
A
- Stimulate Adenylyl cyclase
- odorant receptors
12
Q
alpha q
A
- Phospholipase C
- Acetylcholine muscarinic type 5
13
Q
alpha s
A
- “Stimulate” Adenylyl cyclase
- Ex. beta-adrenergic, Dopamine-1
14
Q
Although Composed of Different Proteins,
All Intermediate Filaments Have
A
- Similar Structural Characteristics
- Conserved Central rod domain: Composed of coiled coil alpha helices that form assembly domain
- Variable NH2 and COOH domains (provide functional specificity).
15
Q
Alzheimer’s Disease Displays
A
- Intracellular Neurofibrillary Tangles of Hyperphosphorylated Tau
- Destabilized Microtubule and Disrupted Neurites
16
Q
Angiogenesis
A
formation of new blood vessels to feed growing tumor
17
Q
APC Tumor Suppressor
A
- Inhibits Wnt Signaling Pathway
- Familial Adenomatous polyposis- Colon cancer
- Mutation in APC causes 1000’s of benign polyps to form in colon.
- Further mutations (in other genes) eventually lead to cancer.
- not related to anaphase promoting comples (also APC)
18
Q
APC/Axin
A
scaffold proteins
19
Q
Appropriately Folded Proteins are
A
- Packaged into Vesicles (COPII) and sent to Golgi for further processing/sorting.
- Vesicle coat proteins help sort/package cargo
And physically “vesiculate” membrane.
20
Q
Are all Internalized Receptors Recycled Back To Plasma Membrane? Why? (and example)
A
- No, sometime a cell wants to inhibit (down-regulate) signaling
- ex: EGF receptor involved in signal transduction
21
Q
ATP Dependent Motor Proteins:
A
- Kinesin
- Dynein
22
Q
autophagy
A
Old Organelles and unwanted cytoplasmic entities can be encapsulated and recycled to lysosome
23
Q
autophagy steps
A
- vesicle nucleation: isolation membrane forms
- vesicle elongation: isolation surrounds unwanted materials
- autophagosome forms
- docking and fusion of lysosome to autophagosome
- vesicle breakdown and degradation
24
Q
Basal Lamina Constitutes
A
a Critical Barrier Through Which Metastasizing Epithelial Carcinomas Much Breech
25
Bcl-2 prevents
Cytochrome C release from mitochondria (anti-apoptotic
26
benign
Moderate, local, non-progressive tumor growth (less aggressive)
27
Both Vesicle and Target Membranes Have Proteins That...
- That Help Target and Tether the Compartments Together
28
BRCA1,2
DNA double strand break repair
29
Brown and Goldstein
- studying Hypercholesterolemia/LDL receptor
- discovered receptor mediated endocytosis pathway which cells use to import LDL from blood
- they were awarded the Nobel Prize in 1986.
30
Burkitt’s Lymphoma
- T(8;14)
- Inappropriately Places Transcription Factor Myc near Ab Producing region
- Inappropriately active promoter… (euchromatin)
- Over-expression of other proteins such as Bcl2 and Bcl3 can occur in a similar manner.
31
Ca++
- stored/sequestered in the smooth (and rough) ER lumen
- is a major cell signaling molecule that is kept at very low concentrations in the cytosol via membrane transporters that pump it (ATP) either out of the cell or into ER lumen for “storage.”
32
Ca++ Exerts Many of its Effects Via
Protein Calmodulin
33
Calcium is a major signaling molecule
And therefore has _____ sequestration/release pathways
many
34
Cancer
Uncontrolled cell growth that invades nearby or distant surrounding tissues.
35
Cancer Causing Mutations Occur In
- Oncogenes: Pro-cancer (Overactive)
- Tumor Suppressor Genes: Anti-cancer (Deleted)
36
Cancer cells secrete
proteases that act on basal lamina and extracellular matrix- facilitating tumor cell migration
37
Cancer Radiation
- Many cancer types: head/neck, breast, cervix, prostate, etc…
38
Cancer surgery
followed by empirically derived treatment regimen targeting specific cancer subtypes:
39
Cancer Therapy
- surgery
- radiation
- chemotherpay
- immunotherapy
40
Cancer Types
- Carcinoma: Epithelial tissue- Skin, Lung, Colon, Breast (90% of all cancers)
- Leukemia: Blood
- Lymphoma: Lymph tissue
- Sarcoma: Connective tissue- Bone, cartilage, muscle
41
Cancerous Environmental Exposure
- Chemicals: Carcinogens (Tobacco smoke)
- Ionizing and UV Radiation: X-rays, Sunlight, Nuclear - Explosions
- Infectious Agents: Viruses (Ex. HPV- cervical cancer)
42
Carbohydrates may be _-_____or _-______
- o-linked or n-linked
43
Caveoli
- are enriched in lipid rafts
- May play a role in non-specific “cell drinking” (maintain PM surface area).
- Some forms of receptor internalization- Linked to signal transduction (Ex. G-protein coupled receptors)
44
CBP has ______ _____________ activity. Which?
- histone acetyltransferase
- activity- which promotes euchromatin formation, and helps to stabilize the transcription machinery complex.
45
Cells Communicate With Each Other Using
Diffusible Extracellular Signals
46
Cells not only need “nutrients” to survive, develop, and differentiate but also require
- growth factor- signals
- different growth factor receptors are expressed in different cell types.
47
Cellular Response is an Orchestrated “Symphony” Integrating ___ __ ____
- all cell signaling
48
Centrosome (MTOC) Nucleates
- microtubules
- centrosome typically is located near the nucleus
49
Chemotherapy
- DNA Replication- “T” synthesis inhibitor (Ex. Fluorouracil) (Skin)
- DNA Replication- Microtubule disrupter (Ex. Taxol) (Many cancer types)
- Signal Transduction- Receptor “blockers:” (Ex. Tamoxifen) (Breast)
- Signal Transduction- Kinase inhibitors (Ex. Gleevac) (Leukemia)
50
Cholesterol is packaged into
LDL (Liver), and delivered to cells via the bloodstream
51
Chromosomal Translocation
Involves
- breaking one chromosome and fusing it with another.
- May occur either during mitosis or meiosis.
52
Classes of Intermediate Filaments
- 6 classes
- Composed of several different proteins
- Are differentially expressed in tissues
- ~8-12nm in diameter
- Relatively static, but assembly can be regulated
- Ex. PO4 of nuclear lamins causes disassembly
53
Clathrin
transport vesicles from the golgi/ plasma membrane to the endosome
54
Clathrin dependent endocytosis
- receptor-mediated
- specific
- ex: LDL import
55
Clathrin Independent Endocytosis
- Mediated by other coat proteins
- Different cargo…
- Controls cell surface area
- (Ex. Caveolin)
56
Clathrin Lattices Promote
Curvature of Plasma Membrane into “large” (~50nM) electron dense “coated pits.”
57
Clathrin “Coat Protein” Monomers
- Assemble Into Triskelions (can also disassemble)
- Bind to the cytoplasmic PM bilayer
- Induce curvature into clathrin-coated “pits.”
58
Coat Independent aka
fluid phase
59
Coat Proteins/Adaptors
Help Sort Cargo for Vesicle Transport to Various Cellular Locales (help in physically budding too).
60
Coated vesicle formation steps
1) coat assembly and cargo selection
2) bud formation
3) vesicle formation
4) uncoating
61
Common Colon Cancer Mutations
- APC
- CTNNB1
- KRAS
- SMAD4
- TGFBR2
- p53
- mismatch repair genes
62
Concentration of Ca++ is ~______ times lower in Cytosol (than extracellular)
10,000
63
Conformational Changes in SNARE Protein Machinery Cause...
- Membrane Fusion
- Vesicle Contents (Ex. Neurotransmitter) are released, and vesicle membrane components added to the plasma membrane.
64
Constitutive Secretion
- all cells undergo it
- Vesicles leave TGN- head straight to plasma membrane/exocytosis to release extracellular matrix proteins, and “insert” plasma membrane proteins
- constant exocytosis
65
Constitutively active Ras
- mutation: no hydrolyze GTP
- present in numerous cancers.
66
COPI
transport vesicles from the golgi to the ER
67
COPII
transport vesicles from the Er to golgi
68
Core complex is formed by
- four α-helices contributed by:
- vSNARE: synaptobrevin,
- tSNARE’s: syntaxin and SNAP-25.
69
Core Glycosylation Function
- Promotes Proper Protein Folding in ER Via Calnexin
70
Core Sugar Transferred onto
- Asn of “ER Translating” Substrate Proteins
- In ER Lumen via Oligosaccharyl Transferase.
71
Cotranslational Import of Nascent Secretory Proteins Into ER Requires
- Requires ER Signal Sequence
- Using GTP, Pore opens and nascent polypeptide is pumped into ER lumen.
- Signal peptidase cleaves off
- Signal sequence during transit.
72
Cotranslational Import of Nascent Secretory Proteins Into ER Steps
1) SRP binds to ER signal sequence and blocks translation
2) SRP binds to SRP receptor, ribosome docks on membrane
3) GTP binds to SRP and SRP receptor, pore opens and polypeptide in inserted
4) GTP is hydrolyzed and SRP is released
5) signal sequence is cleaved by signal peptidase as polypeptide elongates and translocates into ER lumen
6) completed polypeptide is released into ER lumen, ribosome is released, and translocon pore closes
73
Different G-protein Subclasses
- alpha a
- alpha olf
- alpha I
- alpha q
74
Downstream Signaling from EGF Receptor Via GRB2
- GRB2 (via SH2 domain) recognizes/binds PO4-Tyr in receptor
- Recruits Sos (Guanine Nucleotide Exchange Factor).
- GRB2/Sos activate Ras (small monomeric G-protein) by promoting GDP- GTP exchange.
- Activated Ras(GTP) then initiates a cascade of PO4 reactions involving kinases such as MAPK leading to PO4 of target proteins such as transcription factors (Ex. AP1).
- AP1 affects transcription of numerous genes involved in cell growth/division (Ex. G1-S cyclin).
75
Downstream Signaling from EGF Receptor Via GRB2 triggers
- gene expression changes allowing epithelial cell survival and growth
76
Downstream targets of CREB include
genes involved in learning and memory
77
During Mitosis...
Centrosome Duplicates and Microtubules Reorient To Form Mitotic Spindle
78
Dynamin
- Molecular Pinchase
- Severs Vesicle Bud From Donor Membrane.
- Forms a collar around coated vesicle neck
79
dynein moves vesicles in
(-) direction (towards cell interior)
80
Dynein
- is composed of ~12 polypeptide subunits (1.5mDa).
- Heavy Chains- ATPase activity- “walk along microtubule.”
- Dynactin Complex helps Dynein bind Vesicle cargo.
81
Each Golgi Compartment is ...
- Biochemically Distinct, and contain specific resident enzymes.
- Ex. Glucosamine transferase I localizes predominantly to medial cisternae
82
EGF Receptor Stimulation Also Signals Via
- phospholipase C
- GRB2
83
EGF Receptor Stimulation Signaling Via Phospholipase C.
- Ligand Binding, clustering of receptor, and autophosphorylation recruits and activates Phospholipase Cy (also has an SH2 domain).
- Activated Phospholipase Cy Cleaves PIP2 into IP3 and DAG,
- DAG Stimulates PKC
- IP3 stimulates Ca++ release from ER storage- and Calmodulin/Kinase effects
84
Enclosed space within ER is called the
lumen
85
Endocytosis allows...
Import of Large Molecules Into Cell. And keeps membrane size in a steady state equilibrium (counterbalances exocytosis)
86
Endocytosis Steps
1) membrane invaginates, forming a pocket containing macromolecules or other materials from the exterior of the cell
2) pocket begins to pinch off, enclosing the extracellular material
3) membrane closes around the invaginated material, forming a vesicle
4) vesicle separates from the plasma membrane, carrying material from the exterior within a membrane derived from the plasma membrane
87
Endoplasmic Reticulum (ER)
- continuous network of flattened sacs/cisternae
- rough ER, smooth ER (continuous with each other)
- (In the perinuclear space)
88
endosome function
cargo sorting
89
Endosome microdomains sort to
various intracellular locations: Lysosomes, PM or Golgi
90
Endosomes are...
-“Intermediate” Vesicular Sorting Compartments
- Particularly of “incoming” endocytic material
91
Endosomes can mature into...
lysosome
92
Cytochrome P-450
- ~ 60 homologous enzymes
- Prominent enzyme in smooth ER of Liver Hydroxylates substrates.
- substrate -> substrate-OH
- Hydroxylated substrates are more soluble in water (can pass into bloodstream/urine)
93
Epidermal Growth Factor (EGF)
- Tyrosine Kinase Receptor
- Expressed in many tissue types
- Mutations in EGFR are linked to lung cancer.
94
ER Can Make up ~__% of Total Cell Membrane
- ~50%
- the more exocytosis/ secreting it does the more ER there is
95
ER lumen
- Initial Protein glycosylation and folding
- in the rough ER
96
ER Signal Sequence
- ~15-30 aa on extreme NH2 terminus
- Three domains (Basic, Hydrophobic, Polar)
97
ER Translocon
- SRP Receptor
- Ribosome receptor
- Pore protein
- Signal Peptidase
98
Exocytosis
- is the Release of Intracellular Molecules into the extracellular milieu.
- is Constitutive Or Regulated
- adds components (Ex. lipids, proteins within vesicle membrane) into the plasma membrane.
- (vesicle membranes fuse with plasma membrane, and discharge contents.)
99
Function of Carbohydrate transferase enzymes resident in rER membrane
add “core” sugar moieties onto growing polypeptide chain as it enters the ER lumen
100
G alpha q Activates
The Phospholipase C/ PKC Signaling Pathway
101
G alpha q Activating The Phospholipase C/ PKC Signaling Pathway Steps
- G alpha q interacts with and “turns on” Phospholipase C and changes shape
- Phospholipase C cleaves PIP2 into bioactive IP3 and DAG molecules.
- DAG activates Protein Kinase C (PO4 many targets Ex. Na+ channels)
- IP3 travels to ER and binds the IP3 receptor to allow Ca++ release from ER lumen
102
G alpha q Signaling Via IP3 Leads to
Ca++ Release from ER Storage
103
G-Protein Coupled Receptors
- Major Class (super-family) of Signal Transduction Receptors That Signal Via Associated G-proteins.
- All of which display Magnificent 7 (Transmembrane domains)
- Major target for pharmaceutical intervention (~50% of all drugs
- Ex. Muscarinic Acetylcholine receptor.
104
Genes Containing _______ _________ ______Consensus Sequences are “_______” in response to steroid
- appropriate regulatory region
- signaled
105
Genetic causes of cancer
DNA Replication Errors (Ex. DNA Polymerase mistakes, Abnormal cross-over) can cause either inherited (meiosis) or “spontaneous” somatic (mitosis) mutation.
106
germline mutation
- mutation in one copy of RB gene is inherited in all body cells
- mutation in second copy of RB gene in a single cell
- hereditaty retinoblastoma
107
Golgi Function
- Protein processing (Ex. Glycosylation
- packaging and sorting
108
Golgi Apparatus
- is a Processing/Sorting Station for Endomembrane and Secretory Proteins.
- Post-translationally modifies (Differential Glycosylation [different sugar trees added], Phosphorylation, Sulfation), and packages/sorts secretory proteins.
- plays a role in trafficking lipids
109
Golgi Apparatus Consists of
- an Ordered Series of Compartments.
- Flatted sacs (cisternae) 3-8
- Cis: vesicle entry to Golgi
- Medial: processing
- Trans: vesicle exit from Golgi
110
Golgi Network Terminally N-Glycosylates Secretory Proteins.
- pattern ex: high mannose, complex, and hybrid
- 100’s of different Golgi glycosyl transferases differentially expressed in cells/development.
- Variable terminal glycosylation patterns- allow structure/function diversity.
- Ex. Protein targeting to appropriate organelles.
111
Golgi Targeting of Secretory Proteins Steps
1) lysosomal enzyme is synthesized and carbohydrate is added
2) mannose is phosphorylated by sequential activity of 2 enzymes
3) mannose 6-phosphate binds to receptor and the tagged enzymes are packaged in transport of vesicles
4) low pH in late endosome causes dissociation of enzyme and receptor
5) receptor is recycled
112
Golgi Targeting of Secretory Proteins Via
- “Built In” Protein Motifs
- Ex. Mannose-6-phosphate = Lysosome.
113
Growth Factor Associated Receptors
- are proteins kinases
- Act as Dimers
- Dimerization causes them to auto-phosphorylate each other Ser/Thr, Tyr
- Can affect multiple downstream pathways (Ras, PKC, etc..)
114
Growth Factor Tyrosine Kinase Receptor signaling can also lead to....
- intracellular Ca++ release.
- Ex. of Overlapping signaling Pathways.
115
Growth Factors Are Secreted Molecules That...
Act At Short Range to Affect cell growth, division, development, and response to injury
116
GSK3
kinase
117
GTPase =
“pinchase” mechanically separates vesicle from membrane
118
Hereditary Contribution to Cancer Susceptibility hypothesis
- "two hit" hypothesis
119
Heterotrimeric G-proteins Transduce
Signal From Receptor
120
Heterotrimeric G-proteins Transduce Signal From Receptor Steps
- Binding of ligand changes receptor conformation so it can now interact with G-protein.
- G1 conformation change (to active form), so it now prefers GTP over GDP.
- G alpha separates from beta y and modulates downstream target protein function (Ex. Adenyly cyclase).
- Beta y - help localize/anchor to plasma membrane, sometimes “affects” own target (Ex. K+ channel).
- Galpha eventually hydrolyzes GTP (to GDP) becoming inactive- and re-able to rebind beta y
121
Highly Invasive Cancers Down Regulate
- Adhesive Proteins Such as Cadherin
- Tumors also down-regulate glycosyltransferases, hence many tumor cell surface proteins have limited carbohydrate trees.
- (Ex. Mucin “trees” are altered in adenocarcinoma)
122
HNPCC Results From Mutations in
- DNA Mismatch Repair Enzymes allowing microsatellites throughout genome to change copy number
- Ex. (CA)n - (CA)n+1
123
How core glycosylation Promotes Proper Protein Folding in ER Via Calnexi
- 2 Glucoses are trimmed (Glucosidase I)
- Calnexin (chaperone) captures mono-glucosylated protein and promotes proper folding.
- After capture/folding, final glucose is trimmed by Glucosidase II, protein released from Calnexin.
- UDP-glucose:glycoprotein glucosyltransferase (UGGT) enzymes- “sense” proper folding.
- If folded correctly, glycoprotein is free to leave ER and head towards Golgi for further processing.
- If folded incorrectly, UGGT adds back a single glucose so Calnexin can try again...
- If can’t fold, then alpha- Mannosidase removes 1 mannose and protein is degraded via ERAD.
124
How do newly translated membrane associated proteins stay embedded within the ER membrane
they have stop transfer anchor signal
125
How do some “translating” cytosolic ribosomes “know” to go to the ER?
sequences on the amino terminus
126
How EGF receptor works
- Ligand binding causes EGF Receptor dimerization, and autophosphorylation of Tyr residues.
- Phosphorylated Tyr are recognized by SH2 binding domains of proteins such as GRB2 and Phospholipase C.
127
How endosomes mature into lysosomes
- Early endosomes derive from fusion of TGN vesicles with Endocytic vesicles.
- TGN vesicles shuttle “new” hydrolases
- V-type ATPases pump H+ into vesicle lowering pH to ~5.5 = Late Endosome
- Continued pumping of H+ Leads to formation of Lysosomes (pH ~4.5).
128
how the smooth ER synthesizes membrane lipids
- Series of resident ER biosynthetic enzymes make membrane lipids from glycerol, fatty acid precursors, and various polar head groups.
- Note: enzymes are restricted to cytosolic face of ER membrane
- (enzymes near bilayer splice up the the fatty acids into lipids)
129
hypothetical colon cancer mutations
1) APC mutated (benign polyps)
2) Ras mutated (polyps grow large)
3) p53 mutated (leads to metastasis)
130
In mono-ubiquitylation the ub- receptor does..
- sent to sorting endosome
- packaged into vesicle destined for lysosome via ESCRT/Hrs-STAM
- other receptors without Ub tag (ex. LDL receptor) are sorted back to plasma membrane
131
Intermediate filaments are found only in
- vertebrates
- nematodes
- mollusks
132
Intermediate Filaments Form
Stable Intracellular Scaffold For Cell and Provide mechanical strength and stress buffering
133
Intermediate filaments function
- structural support
- maintenance of animal cell shape
- formation of nuclear lamina and scaffolding
- strengthening of nerve cell axons (NF protein)
- keeping muscle fibers in register (desmin
134
Intermediate Filaments Oligomerize in what manner?
- non-polar
- Monomers align with juxtaposed NH2 termini= Dimer
- Two dimers form tetramer = Anti-parallel Protofilament
- Protofilaments “grow” via staggered arrangement
- Intermediate filament = 7-8 protofilaments thick
135
Intermediate filaments structure
- 8 protofilaments joined end-to-end with staggered overlaps
- no know polarity
136
Intracellular Cytoskeleton is Composed of
- 3 different caliber fibers
- microtubules, microfilaments, and intermediate filaments
137
Intracellular part of receptor does?
transduces signal
138
KDEL Motif
- Targets Proteins Back to ER.
- is built into protein primary amino acid sequence
- Aided by receptors/adaptors/coat proteins/rabs.
139
KDEL motif protein targeting steps
- ER resident proteins contain “KDEL” retrieval tags recognized by receptor in Golgi.
- When KDEL protein binds, receptor changes conformation, and gets packaged into COPI transport vesicle for retrograde transport back to ER.
- (Chimeric KDEL proteins are experimentally retained in ER....)
140
Kinesin
moves vesicles in (+) direction (towards cell periphery)
141
Kinesin Structure
- Globular Head: Binds Microtubule, Hydrolyzes ATP (ATP binding site)
- springlike linker region
- Coiled alpha-helix: heavy chain
- stalk
- light chain: attaches to cargo
142
Kinesin transport steps
- ATP hydrolysis is coupled with alteration of Kinesin conformation, resulting in processive attachment/detachment of individual globular feet.
- Kinesin seems to “walk” along microtubule in a foot over foot fashion
143
Lamin Functions
- Maintain nuclear shape
- Anchor Chromatin
- Organize nuclear membrane proteins (Ex. nuclear pores)
- Depolymerize during mitosis- reform upon re-entry into interphase (Regulated via PO4).
144
Ligand activated receptor activates
multiple G-proteins, which in turn activate multiple adenylyl cyclases, etc...
145
Ligand binds receptor- causing
“changes” inside receiving cell.
146
Ligand binds ___________ aspect of receptor- changing receptor ________.
- extracellular
- conformation
147
Ligand bound receptor translocates to? Why?
nucleus to affect transcription of specific genes.
148
Ligand Gated Ion Channel Example
Nicotinic Acetylcholine Receptor: Na+ influx and cell depolarization
149
Ligand Gated Ion Channel Steps
- closed channel is opened with messenger bind to receptor
- ions (Na+, K+, Cl-) move through open channel
- change in electrical properties of cell
150
lipid derivatives
- steroids
- eicosanoids
151
Lipophilic messenger steps
- lipophilic messenger diffuses across the cell membrane
- messenger bind with cytoplasmic or nuclear receptor to make a hormone-receptor complex (in nucleus)
- hormone receptor complex bings to hormone response element (HRE)
- mRNA forms and exits the nucleus to form protein
152
long distance cell communication
- neurotransmitters
- hormones
153
Loss of APC allows
allows β-catenin to inappropriately build up/signal
154
lysosome function
degradation
155
Lysosomes are...
- Digestive Organelles That Degrade Extracellular and Intracellular Substrates.
- Single membrane-bound, multiple lysosomes/cell
- Lumenal side heavily glycosylated- provides protection from interior hydrolases (14 proteases, 2 nucleases, 6 lipases, 13 glycosidases, 7 sulfatases, 5 phosphatases)
- Low pH ~4.0-5.0 partially denatures macromolecules and activates hydrolases
156
Malignant
Uncontrolled, aggressive growth and metastasis to other organs
157
Mannose 6-Phosphate glycosylated proteins
bind appropriate receptors in Trans Golgi allowing import into specific vesicles headed to Lysosome.
158
Many G-Protein Coupled Receptors Have
various receptor subtypes that all act via associated heterotrimeric G-proteins
159
Many MAP’s are regulated by
upstream kinases and interacting proteins
160
Many Steroid Receptors Are
- Intracellular (Cytoplasmic or Nuclear).
- Hydrophobic
161
MAPs Function
- Microtubule-stabilizing/bundling activity
- Regulation of microtubule-mediated transport.
162
Metastasis changes
- cell adhesion and motility allow cancer cells to invade surrounding tissues, blood vessels, and lymph.
- This process is aided by tumor secreted proteases.
163
Metastatic Cancer Development
- > 100 proto-oncogenes
- ~50 tumor suppressors
- Mutation in several is likely required to cause cancer
164
MIcrofilaments Function
- muscle contraction
- amoeboid movement
- cell locomotion
- cytoplasmic streaming
- cell division
- maintenance of animal cell shape
165
Microfilaments Structure
- two intertwined chains of F-actin
- polarity: +,- ends
166
Microtubule Length Changes Tend to Occur Near
cell periphery in interphase cells
167
Microtubules
- polar and dynamic
- ubiquitous (house keeping gene)
- cell structure
- vesicle movement (train tracks)
- mitotic chromosome movement
168
microtubules monomers
- alpha tubulin
- beta tubulin
169
Microtubules are Composed of
- tubulin monomers
170
Microtubules are Play a Major Role in
- Intracellular Motility
- Vesicle/Organelle Movement
- Chromosome Movement During Mitosis
171
microtubules functions
- axonemal: cell motility
- cytoplasmic: organization and maintenance of animal cell shape
- chromosome movements
- disposition and movement of organelles
172
Microtubules Polar Ends
- (+) End: Dynamic grow/shrink faster
- (-) End: Less dynamic oriented toward middle of cell = Centrosome
173
microtubules structure
- hollow tube with a wall consisting of 13 protofilaments
- polarity: +, - ends
174
Mono-Ubiquitylation Causes
- Receptor Internalization and targeting to the lysosome for degradation.
- Method of down-regulating a specific receptor
175
Most Receptors are
- Plasma Membrane Proteins
- Although lipophilic signalling molecules (steroids) have intracellular receptors
176
Most Signaling Molecules are Either...
protein or lipid derivatives
177
Motor MAP’s Traffic Vesicles in ______ Directions.
specific
178
Multiple DNA Mutational Mechanisms
Convert ____ into _____
- proto-oncogenes into oncogenes
179
Mutant (point mutation) Ras
- can’t hydrolyze GTP
- retains constitutively active conformation.
180
Mutation in Dynamin Causes
- Causes Paralysis (Drosophila shibire Phenotype).
- Does not allow “pinching off” of coated vesicles.
- Instead, distended coated pits/vesicles form at plasma membrane.
- No Neurotransmitter vesicle recycling
- No Neuromuscular communication
181
Mutations in Lysosomal Enzymes
Cause
- a Large Number of Inherited Diseases.
- (Lysosomal storage diseases)
- cause over 40 diseases: (Ex. Fabry’s and Tay-Sachs) that are characterized by the build up of specific indigestible substrate (depending on which precise hydrolase enzyme is mutant).
182
Mutations in Multiple Genes are Typically Required for
Metastatic Cancer Development
183
N-Linked
- Common (~50% of all proteins), Occurs on Asn residues.
- Affects nascent protein folding and targeting to organelles.
- Starts in ER (Core glycosylation).
- Variable terminal glycosylation in Golgi allows for diversity in structure/function
184
N-linked Glycosylation of Proteins
- Initiates in the ER.
- Dolichol phophate based “Core” sugar is built on cytosolic side of ER membrane.
- 2-GlcNAc, 9-Mannose
- “Flipped” to ER lumen
- 3-Glucoses added
185
N-linked Glycosylation of Proteins Steps
1) Dolichol phosphate is built into the cytosolic side od the ER membrane
2) step-by-step synthesis of core oligosaccharide
3) translocation from cytosol to ER lumen
4) transfer to protein
5) final processing of oligosaccharide
186
NE alpha 2 Receptor
- Gi
- Inhibits Adenylyl cyclase
- Decreases PKA Activity
- Decreases PO4 of downstream Targets
- Ex. Vasoconstrict
187
NE beta Receptor
- Gs
- Stimulates Adenylyl cyclase
- Increases PKA Activity
- Increases PO4 of downstream Targets
- Ex. Vasodilate
188
Neurons Regulate...
- Exocytosis of Neurotransmitter.
- Vesicles laden with neurotransmitter wait at presynaptic terminus for “release” signal
189
Newer Cancer therapy ideas
- immunotherapy
- Ab’s that inhibit angiogenesis (Ex. Avastin- blocks VEGF) (Colon, Lung, Glioblastoma)
- Genetically engineered (CRISPR) immune cells that attack tumor antigens
- (Ex. Receptors engineered into T cells that recognize tumor antigen) (Acute Leukemia)
- Ab’s that block T-cell inhibition (Ex. Keytruda) (Metastatic solid tumors)
190
Non-endomembrane proteins stay
in cytosol (some eventually imported to other organelles)
191
Normal vs tumor tissue growth
- normal: Cell Cycle Controlled By Checkpoints
- tumor: loss of normal growth control
192
epigenetic/chromatin changes can also play a role in
- cancer progression by affecting gene expression
193
NSF/SNAPS
mediate release/recycling of exocytic SNARE machinery
194
Nuclear Lamins (Type V)
- Provide scaffold-like meshwork of proteins surrounding inner nuclear periphery.
- Lamin A, Lamin B, Lamin C
195
Nuclear lamins class of intermediate filaments
- in all cell types
- form a nuclear scaffold to give shape to nucleus
196
O-linked
- Less common/ rare
- occurs on Ser or Thr residues (compete for ?), in Golgi.
197
Oncogenes
- Often Code for Signaling Proteins: Transcription Factors, Cell cycle/apoptosis regulators.
- Ex. ERBB2 Receptor: Over-expressed in Breast, Ovarian cancer
198
Other Coat Proteins Mediate
- “Clathrin Independent” Endocytosis
- Ex. Calveoli are Smaller “Smooth” Coated Endocytic Vesicles
- Coat protein is Calveolin (small 22kD protein that forms hairpin loops through PM).
- Still requires Dynamin to “pinch.”
199
Over Expression of Bcl-2 Is Associated With
lymphoma
200
Over-expression of truncated EGFR occurs in
a variety of cancers (Ex. Breast, lung).
201
Overlapping triskelions spontaneously assemble into
slightly non-planar lattices, and “coat” underside of plasma membrane forcing it to “curve” inward
202
p53
- a transcription factor regulating cell cycle/apoptosis genes: slows down cell cycle
- is mutated in ~50% of all cancers.
- Inherit one defective copy: Li-Fraumeni syndrome (multiple child hood cancers).
203
Phagocytized Material (bacteria) is Delivered to the?
- Lysosome for Digestion, and Constituent Macromolecules are Recycled.
204
phagocytosis example
macrophage ingestion of bacteria
205
Phosphorylation is a __________ post-translational modification? allowing?
- reversible
- Phosphotases take PO4 group back off
- Thus, some proteins can “toggle” back in forth between different shapes/functions, based on their phosphorylation status.
206
Phosphorylation of a protein substrate causes
a strong negative charge to be added which modulates protein folding/shape and consequent function.
207
Phosphorylation of CREB by PKA Allows it
- to Bind CBP
- Ultimately Up-regulating Expression of Genes Containing CRE’s in their promoter.
208
PKA phosphorylates
- many downstream targets- changing their shape/function.
- (Ex. CREB, K+ channels)
209
PKA phosphorylates a number of
downstream targets on their Ser and Thr residues Such as: K+ channels, Tau, and the transcription factor CREB.
210
PKA phosphorylation inhibits
K+ channels
211
PO4 β-catenin
substrate for SCF-Ub ligase
212
Process of glycogen breakdown in liver
glycogen granule -> glycogen phosphorylase -> glucose-1-P -> phosphoglucomutase -> glucose-6-P -> glucose-6-phosphatase (at smooth er) looses its phosphate -> glucose -> permease (at plasma membrane) -> glucose in blood
213
Production of second messengers (Ex. cAMP), Phosphorylation cascades (Kinases) May...
alter gene expression or have more localized effects (Ex. reorganize cytoskeleton)
214
Production of TRK Oncogene (Thyroid cancer)
Results from
- from a localized chromosomal inversion
215
Protein Calmodulin
- Small protein with four Ca++ binding domains.
- Binding of Ca++ ions changes calmodulin’s conformation allowing interaction with other proteins such as Kinases
- (CaM Kinase I, II, IV etc...).
216
Protein Glycosylation (Polysaccharide) Initiates in the
- the ER (Finishes in Golgi).
217
Protein Kinases
- Add PO4 to Substrate.
- Serine, Threonine Kinases (Ex. PKA) add PO4 to Ser, Thr, of substrate.
- Tyrosine Kinases (Ex. NGF Receptor) auto-phosphorylate own Tyr.
218
Proto-oncogenes
the “normal” version of the oncogene.
219
Quintessential Tumor Suppressor Gene
p53
220
Rab GTPases
- Help Traffic Vesicles to Appropriate Cellular Locales.
- Rab’s can be thought of as “address tags.”
- ~60 Homologous Proteins
221
Rab's
address tags that help tether vesicle to appropriate membrane organelle
222
Ras Mutations Are Associated With What Cancer Types?
- Pancreatic Cancer
- Lung Cancer
- Colon Cancer
- Bladder Cancer
- Leukemia.
223
Receptor Mediated Endocytosis (Clathrin Dependent).
- Classic endocytosis
- Specific extracellular material Ex: Growth factors, cholesterol, receptors, etc
- Concentrated via receptor interaction with adaptor/coat proteins.
- Brought into cell via coated pits/vesicles and sorted by endosomes to appropriate cellular locale
224
Receptor Mediated Endocytosis in Action
Cholesterol Import into Cells
225
Receptor Mediated Endocytosis Steps
1) ligand binds to receptor and they laterally diffuse
2) cluster into cloated pits and Clathrin coated vesicle forms
3) Dynamin pinches vesicle off
4) Vesicle sheds clathrin coat
5) Coat proteins recycled and Uncoated vesicles fuse with endosomes
6) Ligand released and Receptor recycled to PM
7) Endosomes sort material to: Lysosomes, Golgi or Plasma membrane
226
Receptor Mediated Endocytosis of LDL Steps
- LDL binds to LDL receptor, coated pit forms
- coated vesicle forms and is then uncoated
- vesicle fuses with endosome forming early endosome
- Low pH in early endosome helps dissociate LDL cargo from receptor, goes to lysosome w/hydrolytic enzymes to get free cholesterol
- budding off of transport vesicle, recycling endosome forms
- return of LDL receptors to plasma membrane
227
Receptor Sub-Type Dictates
- Ultimate Physiologic Effect
- Same ligand (Ex. Norepi) can have dramatically different effect on downstream cells depending on which receptor the cell is expressing.
228
receptor- ligand binding steps
- receptor- ligand binding
- signal transduction via second messengers
- cellular responses
- changes in gene expression
229
Receptors
- Specific for ligand
- Subject to inhibition
- Note: same ligand can bind multiple receptors (receptor dictates affect)
230
Regulated Secretion
- some cells undergo it
- Vesicles accumulate near PM, and released in response to a signal
- (Ex: Neurons, Pancreatic cells)
231
Regulated Secretion vesicles are ...
docked and primed waiting for Ca++ signal
232
Repartitioning of Lipids in the ER
- lipid bilayer of ER has a cytosol and a ER lumen side
- phospholipid synthesis adds to cytosolic half of the bilayer
- scramblase catalyzes flipping of phospholipid molecules (ensures equal growth on both sides)
- symmetric growth of both halves of bilayer
233
Repartitioning of Lipids in the plasma membrane
- asymmetric lipid bilayer of plasma membrane with cell exterior and cytosol side
- delivery of new membrane by exocytosis
- flippase catalyses flipping of specific phospholipids to cytoplasmic monolayer
- ex: inner leaflet-ethanolamine serine
234
rER Function
- membrane/Secretory Protein biosynthesis
- glycosylation
- folding
235
Response element for Estrogen
5' ag GT cannntg AC ct 3'
236
Response element for Glucocorticoids
5' ag AA cannntg TT ct 3'
237
Response element for Thyroid hormone
5' ag GT catg AC t 3'
238
Retinoblastoma (Rb)
- First Tumor Suppressor Gene to be Identified
- Retinoblastoma normally sequesters E2F, and controls G1 to S transition.
- Loss of Rb function allows E2F to function uncheckedtified
239
Rough and Smooth ER Membrane Are....
Contiguous (and with Nuclear Envelope).
240
rough ER
- Ribosomes on ER membrane
- Flattened sheets
- Synthesize membrane/secretory proteins
- Prominent in secretory cells
- striated/ layered
241
Rough ER is Studded with
Ribosomes- Synthesizing Secretory and Endomembrane System Resident Proteins (translating proteins)
242
Secretory (Endomembrane System) Protein Trafficking Involves
Numerous organelles are involved in moving macromolecules (proteins) into/out of cell.
243
Secretory Protein Pathway
- ER-> Golgi-> Plasma Membrane-> Exocytosis
- Movement aided via vesicular trafficking
244
Secretory Proteins Are Eventually ________ From Cell Via ___________.
- released, exocytosis
- (Membrane embedded proteins are inserted into “appropriate” membrane)
245
Secretory proteins are immediately trafficked to
ER for translation
246
Secretory Proteins “Traffick” From
ER to Golgi and then out towards plasma membrane via vesicles.
247
short distance cell communication
- paracrines
- autocrines
248
signal molecules
- dopamine
- norepinephrine
- epinephrine
249
Signal Recognition Particle (SRP)
- “Recognizes” Signal Sequence
- Transports translating ribosome to ER
250
Signaling Pathways _______ and ________ (or ________) Each Other
- overlap
- complement or counteract
251
smooth ER
- No Ribosomes
- Tubular
- Variable amounts/cell
- Lipid biosynthesis
- Ca++ storage
- Drug detoxification
- Carbohydrate (Glycogen) metabolism
252
Smooth ER Also Aides in
- Glycogen Metabolism (Prominent in Liver)
- Breakdown of stored glycogen into glucose (when blood sugar is low)
- Glucose-6-phosphatase is a resident smooth ER membrane enzyme.
253
Smooth ER Contains Enzymes That...
- metabolize foreign chemicals
- ex:Cytochrome P-450
254
Smooth ER Synthesizes
- Membrane Lipids
- Ex. Phospholipids
255
SNARE Machinery
Forces Lipid Bilayers to Interact
256
SNARES
promote docking/fusion of membranes
257
somatic mutation
- mutation in once copy of RB gene occasionally occurs as cells divide
- mutation in second copy of rb gene in a single retinal cell
- nonhereditary retinoblastoma
258
Steps of Phagocytized Material (bacteria) being Delivered to the Lysosome
1) bacterium binds to receptors and plasma membrane forms pseudopod around bacterium
2) phagocytic vacuole forms
3) transient contact with early and late endosomes during maturation
4) mature lysosome (bacterium broken down by lysosomal hydrolases
259
Internalized Receptors Not Recycled Back To Plasma Membrane Steps
1) ligand (EGF) binding and receptor aggregation
2) autophosphorylation of tyrosines
3) binding of cytosolic proteins with SH2 domains
4) activated PLCy stimulates IP3-DAG pathway
5) activated GRB2-Sos stimulates Ras pathway
6) Ras is inactivated by a GAP
260
Steroid response elements
- similar to each other
- are scattered throughout genome in various promoters.
- each steroid typically controls multiple downstream genes.
261
Synaptotagmin
Ca++ sensor- regulates late steps of exocytosis (vesicle fusion)
262
T-snare (targeT-snare)
contributes other 3 alpha helices, to drive actual membrane fusion
263
Tau (MAP) is implicated in...
Alzheimer's disease and other dementias.
264
Tau binding is regulated by
- by Phosphorylation
- phosphorylation tends to disrupt MT organization
265
Tau Binds and Stabilizes
- microtuules
- binds MT longitudinally and bridges individual tubulin subunits
266
the Largest Diameter Cytoplasmic Filament is?
- microtubules
267
Three major Plasma Membrane receptor subclasses
- Ion channels
- G-protein coupled
- Tyrosine Kinase
268
Tobacco Carcinogens
cause point mutations in p53 (Lung cancer)
269
Trans Golgi Network Sorts
Vesicles/Secretory Protein Cargo Based on “signals/motifs.”
270
transduction cascade
- transmitter
- transmitter activates receptor
- receptor activates G-proteins
- G-protein stimulates adenylyl cyclase to convert ATP to cAMP
- cAMP activates protein kinase A (multiple downstream targets)
271
Transduction Cascades Allows
Amplification/Diversity of Signal
272
Transport of Vesicles Occurs Along
Microtubule “Train tracks.”
273
Triskelions formed from
- 3 clathrin heavy chain polypeptides (192kD)
- 3 clathrin light chain polypeptides (30 -36kD).
274
Trophic Factors
- Are Required to Keep Cells Alive.
- by inhibiting Cytochrome C release from mitochondria- and consequent Apoptosis
- Growth Factors also may increase cyclin expression
275
Truncation deletes
- extracellular domain
- resulting in a constitutively dimerized and active receptor.
276
Tubulin Dimers Associate Steps
1) tubulin dimers
2) oligomers
3) protofilament
4) sheets of protofilament
5) closing microtubule
6) elongating microtubule
277
Tubulin Dimers Associate to Form
- Hollow 25nM Diameter Microtubules.
- Model of Microtubule Assembly.
278
tubulin heterodimer 2 major genes
- alpha-Tubulin, beta-Tubulin,
- 55kDa
- Act as heterodimers
- “Head to Tail” Configuration
279
Tumor Suppressor Genes
- Cause Cancer When They are Missing/Defective.
- Ex. p53 is a transcription factor regulating cell cycle/apoptosis genes.
- Ex. Rb sequesters E2F
- Ex. BRCA1,2: DNA double strand break repair enzymes
280
Tumors Are Characterized by
Massive Cell Growth/Division and thus require significant blood supply (nutrients) to grow beyond 1-2mm in diameter
281
Tumors developing from most tissues- first capillary bed reached is?
lung
282
Tumors developing from stomach and colon- first capillary bed reached is?
Liver
283
Tumors Release
VEGF (Vascular endothelial growth factor) and FGF (Fibroblast growth factor) which stimulate vascular migration and development
284
Tumors Tend to Recruit...
Their Own Blood Supply
285
Two cAMP (Produced by Adenylyl Cyclase) Activate
Protein Kinase A (PKA)
286
V-snare (vesicle snare
contributes one alpha helix,
287
Vesicle traffic specificity mediated by
- adaptor
- coat
- rab proteins
288
Vesicles Function
trafficking
289
Vesicular Coat Proteins
Force Flat membranes to Form Spherical Buds.
290
what causes cancer?
DNA mutations
291
what is release signal (neurotransmitters)?
Ca++
292
What Largely Dictates Metastasis Location?
- blood flow patterns
293
Why are Mutations in DNA Repair Enzymes Particularly Pernicious?
- As They Allow Numerous Mutations To Develop Throughout Genome
294
why so many steps in cell signaling?
to help amplify and allow for more tweaking at each step (more diversification of cells)
295
~__% of Plasma Membrane recycled per hour
25%
