G-BETA-GAMMA INTERACTIONS WITH PH DOMAINS AND RAS-MAPK SIGNALING PATHWAYS

G-protein-coupled receptor signaling and receptor tyrosine kinase (RTK ) signaling are two mechanisms of transmembrane communication used by numerous extracellular agents and stimuli. The beta gamma-subunit comp lex of G proteins mediates many of the functions associated with G-pro tein-coupled receptor signaling and may even provide a means to link G proteins to RTK-initiated cascades. This connection may be mediated b y the pleckstrin homology domain, a modular domain found in many signa ling proteins that interact with G(beta gamma).