GPCR Flashcards
Role of GTP
provides energy for the signal
purpose of GPCR
detect extracellular signal & transduce it into an intercellular response
STRUCTURE of GPCR
N terminal
extracellular domain
7 transmembrane domains
C terminus of protein: heterotrimeric- 3 subunits
what happens at N terminal of GPCR?
chemical binds to it
conformational change within receptor complex which has an impact on C terminal
G protein activation
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
signalling pathway for G alpha S
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
signalling pathway for G alpha I
inhibits: Adenylate (adenylyl) cyclase which converts ATP into cyclic AMP
signalling pathway for G alpha q
activates phospholipase C
PLC breaks PIP2 down (hydolyzes) to IP3 & DAG (key second messengers)
IP3- causes release of Ca2+
DAG- activates protein kinase C
what is PIP2?
membrane phospholipid
IP3 CAUSES?
release of Ca2+
DAG activates?
protein kinase C