GPCRs and Second Messengers

Question 1

How many transmembrane alpha helices does a Gprotein contain

Answer 1

7

Question 2

Where can a large and small ligand bind on a g protein

Answer 2

Large outside the cell membrane

Small can be within the cell membrane

Question 3

When GPCRs activate what molecule dissociates from the G-Protien, and what replaces it?

Answer 3

GDP is dissociated, and replaced by GTP

Question 4

What Components are separate when GPCRs are activated

Answer 4

separate components:
Receptor
Alpha subunits
Beta gamma subunit complex

Question 5

Explain how the alpha subunit changes when activating a second messenger

Answer 5

Alpha subunit is loaded with GTP, finds second messenger and activates it, when doing so it hydrolyzes its GTP into GDP, its inactivated form.
Then recombines with the beta-gamma subunit to recombine on the receptor

Question 6

What does the G protein subtype Gi do?

Answer 6

it is inhibitory for adenylate cyclase protein, reducing cAMP production

Question 7

What does the G protein subtype Gs do?

Answer 7

It is stimulatory for adenylate cyclase protein, increasing cAMP production

Question 8

What does the G protein subtype Gq do?

Answer 8

Activates Phosphoinositide (phospholipase C)

Question 9

What type of G protein is an M2 Muscarinic receptor?

Answer 9

Gi G protein subtype

Question 10

What subtype of G protein is a B1 adrenergic receptor?

Answer 10

Gs G protein subtype

Question 11

What subtype of G protein is an M3 Muscarinic receptor?

Answer 11

Gq G protein subtype (phosphoinositide)

Question 12

Mechanism of action of Gq G Protein subtype overall produces what effect?

Answer 12

Increase in Ca2+ release (useful in muscles)