Which of the following events normally activates a gtp-binding protein? a).gtp hydrolysis by the protein activation of an upstream gtpase-activating proteinb).activation of an upstream guanine nucleotide exchange factorc). phosphorylation of a bound gdp molecule by an upstream phosphorylased). pi release after gtp hydrolysis

Answer;

b). Activation of an upstream guanine nucleotide exchange factor

Explanation;When a ligand activates the G protein-coupled receptor, it induces a conformational change in the receptor that allows the receptor to function as a guanine nucleotide exchange factor (GEF) that exchanges GDP for GTPthus turning the G protein-coupled receptor on.The activated G-protein then dissociates into an alpha (G-alpha) and a beta-gamma complex.