InterPro domain: IPR001711

Phosphatidylinositol-specific phospholipase C ( 3.1.4.11 ), an eukaryotic intracellular enzyme, plays an important role in signal transduction processes [ 1 ] (see IPR001192 ). It catalyzes the hydrolysis of 1-phosphatidyl-D-myo-inositol-3,4,5-triphosphate into the second messenger molecules diacylglycerol and inositol-1,4,5-triphosphate. This catalytic process is tightly regulated by reversible phosphorylation and binding of regulatory proteins [ 2 , 3 , 4 ].

In mammals, there are at least 6 different isoforms of PI-PLC, they differ in their domain structure, their regulation, and their tissue distribution. Lower eukaryotes also possess multiple isoforms of PI-PLC.

All eukaryotic PI-PLCs contain two regions of homology, sometimes referred to as 'X-box' (see IPR000909 ) and 'Y-box'. The order of these two regions is always the same (NH2-X-Y-COOH), but the spacing is variable. In most isoforms, the distance between these two regions is only 50-100 residues but in the gamma isoforms one PH domain, two SH2 domains, and one SH3 domain are inserted between the two PLC-specific domains. The two conserved regions have been shown to be important for the catalytic activity. At the C-terminal of the Y-box, there is a C2 domain (see IPR000008 ) possibly involved in Ca-dependent membrane attachment.

1. The PtdIns-PLC superfamily and signal transduction. Biochim. Biophys. Acta 1092, 49-71
2. Multiple forms of phospholipase C isozymes and their activation mechanisms. Adv. Second Messenger Phosphoprotein Res. 26, 35-61
3. Regulation of inositol phospholipid-specific phospholipase C isozymes. J. Biol. Chem. 267, 12393-6
4. Regulation of phospholipase C by G proteins. Trends Biochem. Sci. 17, 502-6