G proteins are enzymes that bind and hydrolyze GTP to GDP. They are regulated by associated proteins that induce the binding of GTP and are called and that induce the hydrolysis of GTP to GDP and are called .

Explanation:

(A) Heterotrimeric G-proteins are composed of three distinct subunits (α, β, and γ). Receptor activation causes the binding of the G-protein and the α subunit to exchange GDP for GTP, leading (more...) The second class of GTP-binding proteins are monomeric G-proteins (also called small G-proteins).