The alpha-s subunit of G proteins will be activated when __________. A) the alpha s-subunit binds...

The alpha-s subunit of G proteins will be activated when __________.

A) the alpha s-subunit binds to GTP

B) the alpha s-subunit is complexed with the G protein beta and gamma subunits

C) the alpha s-subunit is translocated into the nucleus

D) the alpha s-subunit is phosphorylated

Expert Solution

Dear student , the correct option would be A.

G proteins stand for guanine nucleotide-binding proteins which acts as molecular switch inside cell. G proteins are further classified into two clsses a)monomeric small GTPases and b)heterotrimeric G protein complexes . The latter class comprises alpha , beta , and gamma subunits .

In heterotrimeric G protein complex, beta and gamma subunit exist as beta-gamma dimer . The alpha subunit and tightly held beta-gamma dimer exist together . Now there is also another class of proteins called G protein-coupled receptors , which upon coupling with G proteins induce conformational change . This makes them eligible to function as guanidine nucleotide exchange factor that exchanges GDP to GTP . This exchange induces dissociation of alpha subunit (bound to GTP) from beta-gamma subunit and receptor. this bound form can then furthur activate other signalling pathways.

So , option A would be correct .

Hope this helps!

queen_honey_blossom answered 2 years ago

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