43. Which of the following statements concerning the action of G proteins on adenylate cyclase is true? I. G proteins always serve to activate adenylate cyclase. II. G proteins always serve to inhibit adenylate cyclase. III. Some G proteins activate adenylate cyclase, while others inhibit it. IV. G proteins do not act on adenylate cyclase at all. 9

Some G proteins activate adenylate cyclase, while others inhibit it.

Explanation:

G proteins helps in the signal transduction process that transfer message in the body. GPCRs (G-protein-coupled receptors) are located on the surface membrane of the cell.

The G protein can activates the protein or might deactivate the proteins that helps in the adenylate cyclase. The particular phosphorylation and dephosphorylation process at different sites by the G proteins can result in activation and inactivation of adenylate cyclase.

Thus, the correct answer is option (C).

where are the choice options?