Phosphatidylinositol-specific phospholipase C, X domain (IPR000909)

Short name: PLipase_C_PInositol-sp_X_dom

Overlapping homologous superfamilies

Domain relationships



Phosphatidylinositol-specific phospholipase C, a eukaryotic intracellular enzyme, plays an important role in signal transduction processes [PMID: 1849017]. 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 [PMID: 1419362, PMID: 1319994, PMID: 1335185]. 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 the 'X-box' 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. By profile analysis, we could show that sequences with significant similarity to the X-box domain occur also in prokaryotic and trypanosome PI-specific phospholipases C. Apart from this region, the prokaryotic enzymes show no similarity to their eukaryotic counterparts.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.