Phosphatidylinositol 3-/4-kinase, conserved site
IPR018936
Definition
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 [[cite:PMID:8387896], [cite:PMID:12151228]]. The catalytic domain of PI3/PI4KK has the typical bilobal structure that is seen in other ATP-dependent kinases, divided into an N-lobe and a C-lobe ([pdbe:4HNE]) PMID:24675427. The core of this domain is the most conserved region of the PI3Ks. The N-lobe contains a five-stranded antiparallel β-sheet core flanked by a helical hairpin on one side and a helix on the other. The C-lobe contains helices, which form a helical bundle together with the N--obe helix. The helical bundle is flanked by three β-strands and a helix. Three loops are related to kinase activity, the glycine-rich G-loop, the catalytic loop and the activation loop. The G-loop has been reported to bind to the phosphate group of nucleotides PMID:24675427.
16 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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