Phosphatidylinositol phosphate kinase (PIPK) catalytic domain found in Phosphatidylinositol 5-phosphate 4-kinase type-2 beta (PIP5K2B) and similar proteins
PIP5K2B (EC 2.7.1.149), also known as 1-phosphatidylinositol 5-phosphate 4-kinase 2-beta, or diphosphoinositide kinase 2-beta, or phosphatidylinositol 5-phosphate 4-kinase type II beta, or PI(5)P 4-kinase type II beta, or PIP4KII-beta, or PtdIns(5)P-4-kinase isoform 2-beta, or PIP5KIIbeta, or PIP4K2B, participates in the biosynthesis of phosphatidylinositol 4,5-bisphosphate. It directly regulates the levels of two important phosphoinositide second messengers, PtdIns5P and phosphatidylinositol-(4,5)-bisphosphate (PtdIns(4,5)P2), one of the key metabolic crossroads in phosphoinositide signaling. It regulates the levels of nuclear PtdIns5P, which in turn modulates the acetylation of the tumour suppressor p53. It also interacts with and modulates nuclear localization of the high-activity PtdIns5P-4-kinase isoform PIP4Kalpha. Moreover, PIP5K2B is a molecular sensor that transduces changes in GTP into changes in the levels of the phosphoinositide PtdIns5P to modulate tumour cell growth.