TYPE-SPECIFIC REGULATION OF ADENYLYL CYCLASE BY G-PROTEIN BETA-GAMMA-SUBUNITS

Heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins) dissociate into guanosine triphosphate (GTP)bound alpha-subunits and a complex of beta and gamma-subunits after interaction with receptors. The GTP-alpha subunit complex activates appropriate effectors, such as adenylyl cyclase, retinal phosphodiesterase, phospholipase C, and ion channels. G protein beta-gamma-subunits have been found to have regulatory effects on certain types of adenylyl cyclase. In the presence of G(s-alpha), the alpha-subunit of the G protein that activates adenylyl cyclase, one form of adenylyl cyclase was inhibited by beta-gamma, some forms were activated by beta-gamma and some forms were not affected by beta-gamma. These interactions suggest mechanisms for communication between distinct signal-transducing pathways.