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Biochem 385 Unit 1 > Lecture 3: Signaling > Flashcards

Lecture 3: Signaling Flashcards

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1
Q

5 protein functions in cells

A 
transport proteins
structural proteins
cell signaling proteins
metabolic enzymes
Genomic caretaker proteins
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2
Q

Metabolic enzymes

A

reaction catalysts control metabolic flux

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3
Q

transport proteins

A

have integral membrane proteins and soluble proteins

move ions and small molecs across HYDROPHOBIC membranes

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4
Q

signaling proteins

A

transmit extracellular and intracellular signals by functioning of molecular switches

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5
Q

genomic caretaker proteins

A

maintain integrity and accessibility of genomic info

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6
Q

structural proteins

A

maintain integrity of cell structures and promote changes in cell shape

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7
Q

passive transporter proteins

A

energetically INDEPENDENT

work in RESPONSE to chem gradients

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8
Q

active transporter proteins

A

require NRG from ATP hydrolysis to transport AGAINST chem gradient

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9
Q

structure of membrane lipid

A

polar head faces out of or into cell
hydrophobic fatty acid tails face eachother in center of membrane
tails form vanderwals interactions w/ each other

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10
Q

2 ways things can move across membrane (broad)

A

membrane diffusion

membrane transport proteins (polar molecs)

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11
Q

membrane diffusion

A

hydrophobic molecs diffuse across membrane

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12
Q

membrane transport proteins

A

passive transport

active transport

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13
Q

graphs:

A

diffusion and passive transport channels: rate of translocation incs with solute conc.

passive transport CARRIER and active transport CARRIER: inc then plateau

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14
Q

why do carrier transport rates plateau

A

b/c the carrier can only turn a molec over so fast. conf changes and carrying takes time. theres a point at which carriers are saturated.

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15
Q

Aquaporins

A

passive transporters
highly conserved
channles, water not bound to anything when going through

transport H2O across hydrophobic membranes

tatrameres (4 parts)

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16
Q

where are aquaporins abundant?

A

kidney, sweat gland, and RBC cells

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17
Q

active membrane transporter proteins ex

A

Ca2+-ATPase transporter protein

ATP hydrolysis used to pump Ca2+ ions across cell membrane AGAINS conc gradeint.

steps through lots of confs b/c of AtP binding and hydrolysis.

specific sequence of changes

for muscle contraction. big Ca conc on one side of cell

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18
Q

Prolosec

A

inhibs gastric H+/K+ ATPase protein

treats stomach ulcers

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19
Q

Zoloft

A

inhibits serotonin reuptake transporter protein

depression treatment

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20
Q

Cocaine

A

inhibits dopamine reuptake transporter protein

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21
Q

What is signal transduction?

A

sig. transduction transmits extracellular signals to intracellular places by ligand-activated receptor proteins

doesnt actually move molecs across cell membrane

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22
Q

G protein coupled receptors (GPCRs)

A

very abundant

controll sensory and hormone signaling in specialized cells

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23
Q

Glucagon

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A

signals through membrane GPCR on liver cells

responds to low blood glucose levels. stims cyclic AMP prodiction to inc rate of glycogen degration and glucose export

24
Q

signal transduction def

Study These Flashcards
A

biochem mech. for “transmitting” signals from outside cells to inside

25
Signal transduction cascades/amplification
1 receptor on membrane response to 1st messenger leads to many targets proteins inside cell amplification can happen wherever there is an enzyme
26
levels of signal transduction
``` 1st messenger receptor protein on membrane upstream signalling proeins second messegners downstream signalling proteins target proteins ```
27
what is synonymous with first messenger
ligand
28
phosphorylation
addition of a phosphate group to a protein in order to turn an enzyme on or off
29
first messengersL
small diffusable biomolecs | hormones like insulin and glucagon
30
3 types of first messenger signalling
endocrine (far away) autocrine (to same cell) paracrine (to adjacent cells)
31
Insulin works by...
lowers blood sugar by stimulating glucose uptake | glucagon is opposite
32
Receptor proteins (cellular "gatekeepers"
G-protein-coupled receptors (membrane embedded) Receptor tyrosine kinases (membrane embedded) (what insulin uses) TNF receptor family (membrane embedded) Nuclear receptors
33
Nuclear receptors
gene regulation bind to hydrophobic compounds often bind steroids, they can enter nucleus steroids change conf of proteins to work on gene regulation NOT found on membrane, found inside cells
34
How GPCRs work
1a. GPCR is ACTIVATED when 1st messanger/ligand binds to GPCR Note: The part of GPCR that goes into cytoplasm associates with Heterotrimeric G protein 1b. Conf change at inside of cell due to ligand binding changes assocation with Heterotrimeric G protein 2a. GDP comes off of alpha subunit. GTP binds in its place Note: When GDP is bound to subunit, the protein is INACTIVE 3. When GTP binds, subunits are dissociated and the protein is active 4. Downstream signalling signals another protein/enzyme Note: GTP is basically a timing mechanism. For every G-alpha protein, theres a rate of GTP hydrolysis. When it hydrolyzes back to GDP, it goes back to being inactive
35
Heterotrimeric G-protein
has 3 subunits alpha beta gamma Associate with either GDP or GTP
36
Downstream Signaling
Signal to some other enzyme ex: adenelate cyclase. enzyme that makes cylic AMP (second messanger) cylic AMP signals another downstream target
37
How many transmembrane alpha helicies do GPCRs have?
SEVEN
38
where are GPCRs found?
embedded in the membrane
39
GPCR Protein Rhodopsin
light sesning retinal molecule retinal has conf change when light hits it retinal burried within helicies of rhodopsin, so chaning its conf changes conf of helicies
40
Inactive sate of heterotrimeric G proteins
this is when it associates with the GPCR | G-alpha subunit has GDP bound to it
41
Active state of G proteins:
(after signal binds to GPCR) | GTP is bound to alpha helix of hetotrimeric G protein
42
GTP/GDP influence on proteins (adenylate cyclase ex): ACTIVE state
G alpha-adenylate cyclase complex present position of the switch helix of G alpha proteins changes when GTP is bound G alpha protein is associated with enzyme adenylate cyclase through the switch helix of G alpha protein adenylate cyclase produces second messenger
43
GTP/GDP influence on proteins (adenylatease cyclase ex): INACTIVE state
the G alpha beta gamma complex is present switch helix is associated with G beta and gamma proteins
44
After Ga protein activated...
interacts with adenylate cyclase
45
adenylate cyclase makes...
cyclic AMP
46
Cyclic AMP
activates protein kinase A (PKA) | phosporylates other molecs
47
when cAMP activated by adenlate cyclase
cAMP binds to regulatory subunit, making it fall off then catalytic subunit is acvtive, cAMP phosphylates molecs
48
cGMP
second messenger stimulated by G alpha stimulating enzyme PHOSPHODIESTERASE light absorption into eye
49
some things G alpha proteins stimulates
cGMP cAMP IP3 and DAG NOTE: there are different types of alpha subunits that do different things.
50
cAMP
second messenger stim by G alphas stimulating enzyme ADENYLATE CYCLASE in response to activation of OLFACTORY RECEPTORS
51
IP3 and DAG
second messenger stim by G alpha interacting with PHOSPHOLIPASE C in response to TASTER RECEPTOR activation on tounge
52
Glucagon signaling
binds to g-protein coupled receptor stims signal transduction pathway: adenlate cyclate activated, cAMP produced, cAMP stims protein kinase A protein kinase A has many targets in cell
53
Glucagon
"I'm Hungry" hormone
54
Protein Kinase A and glucagon signaling
``` target what it needs to as needed if glucagon signalling it: 1. turns off glycogen synthesis 2. turn ON glycogen degradation 3. turn ON glucose synthesis ```
55
glycogen
short term storage form of glucose | long term in fat
56
result of glucagon signaling
net glucose export so cell can have enough energy
57
insulin
tells cell to take in glucose to store as glycogen

Biochem 385 Unit 1 (13 decks)

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