In G-proteins, binding of GTP causes which of the following to occur?
A) association of the Gβ and Gγ subunits with a receptor tyrosine kinase
B) dissociation of Gα from the dimer formed by Gβ and Gγ
C) phosphoylation of Gα using the GTP as the phosphorylating agent
D) guanylation of Gβ which promotes dissociation and activation of Gα
E) none of the above

Question

Quizplus · Accepted Answer

When GTP binds to G-proteins, it causes a conformational change in the Gα subunit, leading to its dissociation from the Gβγ dimer, which can then interact with downstream effectors. This is known as Gα activation. Choice A is incorrect because Gβ and Gγ subunits do not associate with receptor tyrosine kinases upon GTP binding. Choice C is incorrect because GTP does not phosphorylate Gα. Choice D is incorrect because guanylation of Gβ does not promote activation of Gα.

In G-Proteins, Binding of GTP Causes Which of the Following