In enzymology, a 1-phosphatidylinositol 4-kinase (EC 126.96.36.199) is an enzyme that catalyzes the chemical reaction
ATP + 1-phosphatidyl-1D-myo-inositol
ADP + 1-phosphatidyl-1D-myo-inositol 4-phosphate
Thus, the two substrates of this enzyme are ATP and 1-phosphatidyl-1D-myo-inositol, whereas its two products are ADP and 1-phosphatidyl-1D-myo-inositol 4-phosphate.
This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing groups (phosphotransferases) with an alcohol group as acceptor. The systematic name of this enzyme class is ATP:1-phosphatidyl-1D-myo-inositol 4-phosphotransferase. Other names in common use include phosphatidylinositol kinase (phosphorylating), phosphatidylinositol 4-kinase, phosphatidylinositol kinase, type II phosphatidylinositol kinase, PI kinase, and PI 4-kinase. This enzyme participates in inositol phosphate metabolism and phosphatidylinositol signaling system.