Phosphoinositide 3-kinase, catalytic domain (IPR035448)

Short name: PI3Kc

Overlapping homologous superfamilies

Domain relationships



PI3Ks catalyze the transfer of the gamma-phosphoryl group from ATP to the 3-hydroxyl of the inositol ring of D-myo-phosphatidylinositol (PtdIns) or its derivatives. PI3Ks play an important role in a variety of fundamental cellular processes, including cell motility, the Ras pathway, vesicle trafficking and secretion, immune cell activation and apoptosis [PMID: 9255069, PMID: 10580505].

They can be divided into three main classes (I, II, and III), defined by their substrate specificity, regulation, and domain structure. Class I PI3Ks are the only enzymes capable of converting PtdIns(4,5)P2 to the critical second messenger PtdIns(3,4,5)P3. Class I enzymes are heterodimers and exist in multiple isoforms consisting of one catalytic subunit (out of four isoforms) and one of several regulatory subunits [PMID: 10580505]. Class II PI3Ks comprise three catalytic isoforms that do not associate with any regulatory subunits. They selectively use PtdIns as a substrate to produce PtsIns(3)P [PMID: 17371240]. Class III PI3K was first identified as a vacuolar sorting protein in yeast known as Vps34. Unlike other PI3Ks, the Vps34 lipid kinase specifically utilizes phosphatidylinositol as a substrate, producing the single lipid product PtdIns3P [PMID: 17371248].

Contributing signatures

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