Enzymes of the phospholipase C family catalyze the hydrolysis of phospholipids to yield diacylglycerols and water soluble phosphorylated derivatives of the lipid head groups. A number of these enzymes have specificity for phosphoinositides. Of the phosphoinositide specific phospholipase C enzymes, C beta is regulated by heterotrimeric G protein coupled receptors, while the closely related C gamma 1 and C gamma 2 enzymes are controlled by receptor tyrosine kinases. The C gamma 1 and C gamma 2