CDP Diacylglycerol Inositol-3-Phosphatidyltransferase (CDIPT)

Phosphatidylinositol breakdown products are ubiquitous second messengers that function downstream of many G protein-coupled receptors and tyrosine kinases regulating cell growth, calcium metabolism, and protein kinase C activity. Two enzymes, CDP-diacylglycerol synthase and phosphatidylinositol synthase, are involved in the biosynthesis of phosphatidylinositol. The deduced 213-amino acid CDIPT protein is highly conserved in yeast and mammals. Northern blot analysis revealed ubiquitous expression of a 2.1-kb CDIPT transcript, with slightly higher levels in liver and skeletal muscle than in other tissues. Functional analysis showed that expression of CDIPT in COS cells caused an approximately 24-fold increase in PIS activity and in PtdIns:Ins exchange activity.