GPCR

Question 1

Role of GTP

Answer 1

provides energy for the signal

Question 2

purpose of GPCR

Answer 2

detect extracellular signal & transduce it into an intercellular response

Question 3

STRUCTURE of GPCR

Answer 3

N terminal
extracellular domain
7 transmembrane domains
C terminus of protein: heterotrimeric- 3 subunits

Question 4

what happens at N terminal of GPCR?

Answer 4

chemical binds to it
conformational change within receptor complex which has an impact on C terminal

Question 5

G protein activation

Answer 5

signalling molecule binds to the GPCR and G-protein alpha subunit exchanges GDP for GTP
alpha subunit dissociates from beta and gamma subunits and triggers a cellular response
GTP is hydrolysed to GDP and signalling molecule comes off
alpha subunit comes back together with the receptor and the beta and gamma subunits

Question 6

signalling pathway for G alpha S

Answer 6

stimulates:
Adenylate (adenylyl) cyclase converts ATP into cyclic AMP
cAMP is a key second messenger in cells
activates protein kinase A, phosphorylation of target proteins

Question 7

signalling pathway for G alpha I

Answer 7

inhibits: Adenylate (adenylyl) cyclase which converts ATP into cyclic AMP

Question 8

signalling pathway for G alpha q

Answer 8

activates phospholipase C
PLC breaks PIP2 down (hydolyzes) to IP3 & DAG (key second messengers)
IP3- causes release of Ca2+
DAG- activates protein kinase C

Question 9

what is PIP2?

Answer 9

membrane phospholipid

Question 10

IP3 CAUSES?

Answer 10

release of Ca2+

Question 11

DAG activates?

Answer 11

protein kinase C