Question

To regain sensitivity for future stimuli which of the following needs to be inactivated?

Question options:

	GPCR
	G Protein
	Effector protein
	All of them

Answer 1

Answer :- d. ) All of them. GPCR, G protein and Effector protein.

To regain sensitivity for future stimuli all of them needs to be inactivated.

GPCR are ubiquitous in mammalian cells and present intricate mechanism for cellular signalling and communication. GPCR signalling was identified to occur vectorially through hetero trimeric G proteins that are negatively regulated by GRK ( G protein couple receptor kinase) and arrestin effectors.

G protein mediated GPCR signalling is a highly amplified system . Upon activation, GPCRs guanine nucleotides exchange activity last long enough to induce activation of numerous individual G proteins. Activates G proteins provide further signal amplification owing to alpha subunit ability to produce many second messenger molecules during time it remain bound to an effector enzyme . Thus, ligand binding to the receptors activates their associated G protein , which then activates an effector enzyme to generate an intracellular second messenger. So, in this way small amount hormone released from a distant part of a multicellular organisms can profoundly influence the function of a distinct target cell.