Regulation of effectors by G-protein alpha- and beta gamma-subunits - Recent insights from studies of the phospholipase C-beta isoenzymes

Both the alpha-and beta gamma-subunits of heterotrimeric guanine nucleotide-dependent regulatory proteins (G-proteins) couple members of the heptahelical class of cell-surface receptors to a diverse range of signal-generating effectors including retinal cyclic GMP phosphodiesterase, ion channels, adenylylcyclases, phosphoinositide 3-kinase, and members of the beta-class of inositol lipid-specific phospholipases C. Although the molecular details of the G protein-regulated phospholipase C system were elucidated comparatively recently, these enzymes have become 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 provided some important insights into the interplay between G-proteins and their effecters and promises to reveal the mechanisms by which G-protein alpha- and beta gamma-subunits selectively associate with and activate effectors. (C) 1997 Elsevier Science Inc.