G Protein Coupled Receptors

Question 1

Where are g-protein coupled receptors located?

Answer 1

Membrane

Question 2

Enzyme responsible for cAMP formation?

Answer 2

Adenylyl cyclase

Question 3

What is cAMP?

Answer 3

Nucleotide synthesised within cell from ATP byaction of adenylyl cyclase

Question 4

What do protein kinases do?

Answer 4

Regulate the function of many different cellular proteins by controlling protein phosphorylation

Question 5

Two key second messenger pathways controlled by receptors via G proteins

Answer 5

Adenylyl cyclase and phospholipase c

Question 6

Purpose of G protein coupled receptor

Answer 6

Detect extracellular signal and transduce a cellular response

Question 7

Structure of GPCR

Answer 7

• Has 7 transmembrane domain
• coupled to G protein heterotrimeric G protein complex
• agonist binding side

Question 8

How is G protein activated

Answer 8

Signal molecule binds to G protein- coupled receptor
a subunit exchanges GDP for GDP
a subunit dissociates from b +y subunits which trigger cellular response
GTP is hydrolysed and signal molecule comes off receptor
a subunit comes back together with receptor and b+y subunits

Question 9

Galphai and galphas have differential effects on this enzyme

Answer 9

Adenylate cyclase

Question 10

Enzyme activated by galphaq

Answer 10

Phospholipase C

Question 11

Enzyme activated by cAMP

Answer 11

Protein kinase A

Question 12

What is broken drown into IP3 and DAG?

Answer 12

PIP2

Question 13

cAMP is what type of messenger?

Answer 13

Key secondary messenger

Question 14

What does cAMP go on to do?

Answer 14

Activate protein kinase A, phosphorylation of target proteins,

Question 15

PIP2 is?

Answer 15

A membrane phospholipid

Question 16

PLC

Answer 16

Enzyme which breaks down phospholipids