Phosphoinositide-specific phospholipase C (PLC) plays a crucial role in the initiation of receptor mediated signal transduction through the generation of the two second messengers, inositol 1,4,5-triphosphate and diacylglycerol from phosphatidylinositol 4,5-bisphosphate. There are many mammalian PLC isozymes, including PLC (beta)1, PLC (beta)2, PLC (beta)3, PLC (beta)4, PLC (gamma)1, PLC (gamma)2, PLC (delta)1,PLC (delta)2 and PLC E). PLC (beta)s are the only PLC isforms that are regulated by G protein subunits and are activated by a heterotrimeric GTP-binding protein linked to various cell surface receptors. Two alternatively spliced forms (1,181 and 1,166 amino acids) of PLC (beta)2 are generated in hematopoietic cells that differ in the carboxyl-terminal sequence implicated in interaction of PLC (beta) enzymes with G(alpha)q.The pleckstrin homology domain of PLC (beta)2 is required for its targeting to the membrane and for substrate hydrolysis and its linker region exerts an inhibitory efect on basal PLC (beta)2 activity. PLC (beta)2 plays a major role in platelet activation and is mainly expressed in the periphery of the islet and acinar cells in rat pancreas.