G protein linked Flashcards

1
Q

structure of a G protein coupled receptor

A

they are 7 transmembrane receptors so have 7 transmembrane helices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the difference between the first and secondary messenger

A

first messenger is the ligand that binds the receptor

secondary messenger is the molecule produced inside the cell in response to the activation of the ligand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

structure of a G protein

A

3 domains, alpha beta gamma
beta and gamma domains never separate
alpha subunit can bind GTP/GDP and dissociate from beta/gamma domains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

steps of G protein activation cycle

A
  1. hormone binds to G protein coupled receptor and causes a conformational change
  2. Activated receptor binds to G protein and triggers release of GDP
  3. GTP binds to alpha subunit and alpha subunit disscoates from beta/gamma
  4. Alpha subunit binds to effector and activates it
  5. GTP is hydrolyses and alpha subunit reassociates with beta/gamma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

examples of effectors

A

adenylyl cyclase, phospholipase C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does adenylyl cyclase do

A

converts ATP to cyclic AMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how is amount of cAMP regulated

A
adenylyl cyclase is regulated by types of alpha subunit on the G protein 
G alpha (I) inhibits adenylyl cyclase 
G alpha (S) stimulates adenylyl cyclase 
net amount of cAMP produced is regulated by the battle between G alpha (I) and G alpha (S)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the function of cAMP

A

it activates PKA by binding to its 2 regulatory subunits

this releases its 2 active catalytic subunits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is CREB and what does it target

A

PKA phosphorylates CREB which is a transcription factor

once phosphorylated it can bind to other transcriptional transactivators to mediate transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does phospholipase C do

A

it is a downstream effector that converts PIP2 into IP3 and DAG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the importance of IP3

A

it binds to its receptor on the ER
this allows the ER to release calcium into the cytosol
release calcium binds to channel to facilitate more release in positive feedback (up to certain concentration)
calcium activates PKC so it can phosphorylate target proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

role of inositol

A

inositol lipids are phosphorylated to form PIP2 which is then cut by phospholipase C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly