Question

8. Can G-protein coupled receptors produces its effects directly? If not, how does it open ion channels?   What kind of enzyme is activated by G-protein coupled receptors? Name one example.

9. (a) If a neurotransmitter is exerting fast function, what kind of receptor does it use, e.g. glutamate in the brains.

(b) If a neurotransmitter is exerting continuous functions, what kind of receptor does it use, e.g. norepinephrine activates heartbeat.

Answer 1

Ans 8) No, the G-protein coupled receptors are not able to show their effect directly. It detects molecules outside the cell and enables activation of internal signal transduction pathways and impart the cellular response. It helps in opening the ion channel by undergoing a conformation change when a ligand binds to the receptor. The GPCR is able to activate an associated G protein by exchanging GDP bound to G protein for GTP. One of the examples is the activation and functioning of the cAMP signal pathway.