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Biochem 385 Unit 1 > Lecture 3: Signaling > Flashcards

Lecture 3: Signaling Flashcards

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

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

A

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

25
Q

Signal transduction cascades/amplification

A

1 receptor on membrane response to 1st messenger leads to many targets proteins inside cell

amplification can happen wherever there is an enzyme

26
Q

levels of signal transduction

A 
1st messenger
receptor protein on membrane
upstream signalling proeins
second messegners
downstream signalling proteins
target proteins
27
Q

what is synonymous with first messenger

A

ligand

28
Q

phosphorylation

A

addition of a phosphate group to a protein in order to turn an enzyme on or off

29
Q

first messengersL

A

small diffusable biomolecs

hormones like insulin and glucagon

30
Q

3 types of first messenger signalling

A

endocrine (far away)
autocrine (to same cell)
paracrine (to adjacent cells)

31
Q

Insulin works by…

A

lowers blood sugar by stimulating glucose uptake

glucagon is opposite

32
Q

Receptor proteins (cellular “gatekeepers”

A

G-protein-coupled receptors (membrane embedded)
Receptor tyrosine kinases (membrane embedded) (what insulin uses)
TNF receptor family (membrane embedded)
Nuclear receptors

33
Q

Nuclear receptors

A

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
Q

How GPCRs work

A

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
Q

Heterotrimeric G-protein

A

has 3 subunits
alpha
beta gamma
Associate with either GDP or GTP

36
Q

Downstream Signaling

A

Signal to some other enzyme
ex: adenelate cyclase.
enzyme that makes cylic AMP (second messanger)
cylic AMP signals another downstream target

37
Q

How many transmembrane alpha helicies do GPCRs have?

A

SEVEN

38
Q

where are GPCRs found?

A

embedded in the membrane

39
Q

GPCR Protein Rhodopsin

A

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
Q

Inactive sate of heterotrimeric G proteins

A

this is when it associates with the GPCR

G-alpha subunit has GDP bound to it

41
Q

Active state of G proteins:

A

(after signal binds to GPCR)

GTP is bound to alpha helix of hetotrimeric G protein

42
Q

GTP/GDP influence on proteins (adenylate cyclase ex):

ACTIVE state

A

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
Q

GTP/GDP influence on proteins (adenylatease cyclase ex):

INACTIVE state

A

the G alpha beta gamma complex is present

switch helix is associated with G beta and gamma proteins

44
Q

After Ga protein activated…

A

interacts with adenylate cyclase

45
Q

adenylate cyclase makes…

A

cyclic AMP

46
Q

Cyclic AMP

A

activates protein kinase A (PKA)

phosporylates other molecs

47
Q

when cAMP activated by adenlate cyclase

A

cAMP binds to regulatory subunit, making it fall off
then catalytic subunit is acvtive,
cAMP phosphylates molecs

48
Q

cGMP

A

second messenger stimulated by G alpha stimulating enzyme PHOSPHODIESTERASE
light absorption into eye

49
Q

some things G alpha proteins stimulates

A

cGMP
cAMP
IP3 and DAG

NOTE: there are different types of alpha subunits that do different things.

50
Q

cAMP

A

second messenger stim by G alphas stimulating enzyme ADENYLATE CYCLASE in response to activation of OLFACTORY RECEPTORS

51
Q

IP3 and DAG

A

second messenger stim by G alpha interacting with PHOSPHOLIPASE C in response to TASTER RECEPTOR activation on tounge

52
Q

Glucagon signaling

A

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
Q

Glucagon

A

“I’m Hungry” hormone

54
Q

Protein Kinase A and glucagon signaling

A 
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
Q

glycogen

A

short term storage form of glucose

long term in fat

56
Q

result of glucagon signaling

A

net glucose export so cell can have enough energy

57
Q

insulin

A

tells cell to take in glucose to store as glycogen

Biochem 385 Unit 1 (13 decks)

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