Upon binding to its ligand the GPCR becomes activated and Question options: inactivates G protein by...

Upon binding to its ligand the GPCR becomes activated and

Question options:

	inactivates G protein by changing its affinity for GDP and causes it to exchange it for GTP
	activates G protein by phosphorylating it
	activates G protein by changing its affinity for GDP and causes it to exchange it for GTP
	activates G protein by changing its affinity for GTP and causes it to exchange it for GDP

Expert Solution

Answer: activates G protein by changing its affinity for GDP and causes it to exchange it for GTP.

G protein coupled receptors have 7 transmembrane segments that loop in and out of cell membrane. The part of the receptor that protrudes into the cytoplasm is coupled to G proteins.G proteins are trimeric that is have 3 parts.alpha,beta, gamma subunits. When G protein is not active the 3 subunits form a complex that binds GDP on alpha subunit. When ligand bind to extracellular portion of receptors the complex undergoes a conformational change that leads to association of GDP bound trimeric G protein with the cytoplasmic portion of receptor.this causes exchange of GDP for GTP. This exchange causes alpha subunit to dissociate from complex and interact with intracellular signaling proteins.these proteins alters the activity of ion channels or enzymes like adenyl cyclase,phospholipase c that alter cell physiology.

gladiator answered 2 years ago

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