Domain

Phosphatidylinositol 3-/4-kinase, catalytic domain (IPR000403)

Short name: PI3/4_kinase_cat_dom

Domain relationships

Description

Phosphatidylinositol 3-kinase (PI3-kinase) (EC:2.7.1.137) [PMID: 1322797] is an enzyme that phosphorylates phosphoinositides on the 3-hydroxyl group of the inositol ring. The three products of PI3-kinase - PI-3-P, PI-3,4-P(2) and PI-3,4,5-P(3) function as secondary messengers in cell signalling. Phosphatidylinositol 4-kinase (PI4-kinase) (EC:2.7.1.67) [PMID: 8194527] is an enzyme that acts on phosphatidylinositol (PI) in the first committed step in the production of the secondary messenger inositol-1'4'5'-trisphosphate. This domain is also present in a wide range of protein kinases, involved in diverse cellular functions, such as control of cell growth, regulation of cell cycle progression, a DNA damage checkpoint, recombination, and maintenance of telomere length. Despite significant homology to lipid kinases, no lipid kinase activity has been demonstrated for any of the PIK-related kinases [PMID: 12456783].

The PI3- and PI4-kinases share a well conserved domain at their C-terminal section; this domain seems to be distantly related to the catalytic domain of protein kinases [PMID: 8387896, PMID: 12151228]. The catalytic domain of PI3K has the typical bilobal structure that is seen in other ATP-dependent kinases, with a small N-terminal lobe and a large C-terminal lobe. The core of this domain is the most conserved region of the PI3Ks. The ATP cofactor binds in the crevice formed by the N-and C-terminal lobes, a loop between two strands provides a hydrophobic pocket for binding of the adenine moiety, and a lysine residue interacts with the alpha-phosphate. In contrast to protein kinases, the PI3K loop which interacts with the phosphates of the ATP and is known as the glycine-rich or P-loop, contains no glycine residues. Instead, contact with the ATP -phosphate is maintained through the side chain of a conserved serine residue.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0016773 phosphotransferase activity, alcohol group as acceptor

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam
GENE3D
SMART
PROSITE profiles