Flashcards in Final 3 Deck (119):
Exocytosis that requires an external signal, a specific sorting signal on the vesicles, a clathrin coat, and increase of calcium
Exocytosis that serves to release components of ECM or just deliver newly PM proteins
Why would a lysosome deposit its contents outside the cell?
Mark organelles and membrane domains in late secretory pathway
What adds a phosphate onto the inositol ring of phosphatidylinositol
What removes a phosphate on the inositol ring of phsophatidylinositol?
How is neurotransmitter secretion very rapid?
Regulated by calcium
WHere does proteolytic processing occur?
What holds SNARE proteins "partially-zipped up"
Calcium snesor protein that allows the release of vesicle content by membrane fusion
Example of compound exocytosis which provides a very large release of material over a short period of time
Histamines from mast cells
What kind of cells contain GLUT4
Insulin responsive cells (adipose, muscle)
Two compositionally distinct and different PMs
Where is the decision of what membrane a vesicle should go to in a polarized cell made?
TGN or all go to one membrane, and undergo endocytosis and sorting
How is iron transported into the cell?
Fluid-phase endocytosis for uptake of fluids and solutes
Coat protein responsible for majority of vesicular traffic between TGN and PM
Composition of clathrin coats
Triskelion: 3 heavy chains and 3 light chains
Coat used for pinocytosis
Polyhedral superstructures that clathrin triskelion form
GTPase that constricts the neck of a newly formed coated pit to form a vesicle
How is a clathrin coat removed?
HSP70 family of chaperones and its ATPase actiity
Storage form of cholesterol and primary vehicle for cholesterol transport in blood
Low-density lipoprotein (LDL)
Where in the cell are LDL particles broken down?
Clusters of LDL receptors in the PM
What does the cytosolic portion of LDL receptors do once associated with clathrin adapters?
Nucleates binding of a few clathrin triskelions to form coated pit
What happens to LDL receptors after endocytosis
Recycled into PM
How is LDL freed from its receptor?
pH change due to endosome
Separates and sequesters material to be degraded from material to be recycled
Mulitvesicular bodies (MVBs)
How are proteins recognized as needed to be degraded in MVBs?
Cytosolic protein complex that results in a specific accumulation of tagged protein into endosomal membrane invagination
Ingestion of large particles restricted to macrophages and neutrophils
Movement of endocytosed material across the entire clel in membrane enclosed compartment
What do cells unstimulated by insulin do?
Import glucose through the transporter
What do cells stimulated by insulin do?
Release glucose through exocytosis
Chemical bond formation linked to membrane transport process
High-energy electrons from NADH used to set up a proton gradient across IMM
Electron transport chain
Beta-barrel proteins on OMM
What size molecules are porins permeable to?
Location of TCA and the source of NADH
What is the movement of mitochondria mediated by?
What generates more energy, FADH2 or NADH?
How many electrons does a NAD+ accept?
iElectrochemical gradient of protons in the mitochondria
Proton motive force (PMF)
What is the real name for ATP synthesis via electron transport chain
What does the complete oxidation of one glucose yield?
2 NADH, 2 ATP, 2 pyruvate
What are 2 pyruvates oxidized to?
8 NADH, 2 FADH, 2 GTP
How many ATPs are produced per glucose?
What kind of pump is ATP synthase?
Mobile electron carrier that can carry 1 or 2 electrons and is embedded into the membrane
How is uniquinone embedded into the membrane?
What does uniquinone shuttle electrons to and from
From complex I to complex III
Soluble protein with bound heme group
What does cytochrome c shuttle electrons to and from
complex III to complex IV
Name of complex I
Name of complex III
Name of complex IV
Uncouple electron transport from ATP synthesis
2 examples of uncouplers
Part of ATP synthesase that is intermembrane
Part of ATP synthesase that surrounds stalk with 6 subunits
Name of complex II
What does complex II do?
Accepts two electrons from succinate
Signaling to self
Local signaling to a close group of cells
Signaling distributed throughout bloodstream
Signaling based on physical contact
Contact dependent signaling
Difference between endocrine and synaptic signaling
Endocrine are long-livd
Most direct path of ligand signaling
Intracellular receptors (e.g. steroid hromones)
Why are steroid hormones able to use intracellular receptors?
They are lipid soluble so can pass right through PM
4 examples of small G-proteins
Ras, Rab, Rho, Ran
How many transmembrane domains do G-protein receptors have?
What happens when GDP-bound g-proteins are turned on?
ALpha dissociates from beta-gamma
What is the alpha subunit of g-proteins postranslationally modified by?
What is the gamma subunit of g-proteins postranslationally modified by?
Enzymes that have their activity modulated by interaction with a g-protein
Enzyme that converts ATP to cAMP
cAMP initiates a protein kinase cascade by activating what?
Protein Kinase A (PKA)
3 functions of cAMP
cortisol secretion from adrenal cortex, glycogen breakdown in muscle and liver, triacylglycerol breakdown in fat
In muscles, what does PKA activation lead to?
Activation of phosphorylase kinase, leading to glycogen breakdown
What gene regulatory protein does PKA activate?
cAMP regulatory element binding protein (CREB)
What does CREB do?
Changes transcription of genes that contain a cAMP regulatory element (CRE)
Enzyme that cleaves (PI(4,5)P2) into diacylglycerol and IP3
What does formation of IP3 do?
Opens Ca channel and releases Ca into the cytosol from ER
After opening by IP3, what does released Ca bind to?
Protein Kinase C (PKC)
Where are Ca concentrations kept high?
ER and outside cell
Regulatory Ca binding protein for muscle contraction
Calcium sensor for neutrotransmission
Multipurpose calcium receptor involved in many responses
Structure of calmodulin
Four EF hands (ca binding domains)
Main targets of calmodulin
Protein kinase involved in smooth muscle contraction
Myosin light chain kinase
Protein kinase inolved in glycogen breakdown
Calcium-dependent protein kinase whose activity persists even after the calcium signal has faded
CaM Kinase II
How does ca-calmodulin activate CaM Kinase II?
BInds to inhibitory domain, liberating it
Single-span membrane proteins that oligomerize in response to ligand binding
Receptor tyrosine kinases (RTKs)
What kind of protein is the insulin receptor?
What kind of protein are RTKs?
What is the typical method of oligomerization that RTKs undergo?
What does receptor oligomerization of RTKs lead to?
Activation of kinase domain by autophosphorylation
What happens once RTKs become autophosphorylated?
Receptor increases its kinase activity towards substrates
Binds specifically to phosphotyrosine in RTKs
Src Homology Region 2 domain (SH2)
Binds to proline rich motifs in RTKs
Pleckstrin Domain (PH)
What membrane lipid do PH domains associate with?
3 enzymes recruited to PDGF receptor by its SH2 domain
PI3 kinase, Ras GAP, PLC-gamma
Primary target of Ras
What cascade is Raf-1 the first element of?
Signal that tells a cell to divide
Through what molecule does Ras activation generate new membrane lipids?
Receptors that rely on its associated kinases to cross phosphorylate one another
Tyrosine kinase associated receptors
Target of Jak kinases
Role of STAT
Regulator of gene expression
What kind of receptors do TGF-beta use?
Activated TGF-beta activates what kind of gene regulatory proteins?
Ligands for receptor guanylyl cyclases
What do ANP and BNP do?
Regulate salt and water balance
What does cGMP activate?
Membrane bound singaling protein expressed on developing nerve cells