REGULATION OF EFFECTORS BY G-PROTEIN ALPHA-SUBUNIT AND BETA-GAMMA-SUBUNIT - RECENT INSIGHTS FROM STUDIES OF THE PHOSPHOLIPASE C-BETA ISOENZYMES

Both the alpha-and beta gamma-subunits of heterotrimeric guanine nucle otide-dependent regulatory proteins (G-proteins) couple members of the heptahelical class of cell-surface receptors to a diverse range of si gnal-generating effectors including retinal cyclic GMP phosphodiestera se, ion channels, adenylylcyclases, phosphoinositide 3-kinase, and mem bers of the beta-class of inositol lipid-specific phospholipases C. Al though the molecular details of the G protein-regulated phospholipase C system were elucidated comparatively recently, these enzymes have be come an important model for investigations of the process of G-protein effector coupling. A combination of molecular biological, biochemical , and structural studies using the phospholipase C-beta enzymes has pr ovided some important insights into the interplay between G-proteins a nd their effecters and promises to reveal the mechanisms by which G-pr otein alpha- and beta gamma-subunits selectively associate with and ac tivate effectors. (C) 1997 Elsevier Science Inc.