InterPro domain: IPR011009

Protein kinases ( IPR000719 ) modify other proteins by chemically adding phosphate groups to them. This process is fundamental to most signalling and regulatory processes in the eukaryotic cell [ 1 ].

The protein kinases contain a catalytic core that is common to both serine/threonine and tyrosine protein kinases. The catalytic domain contains the nucleotide-binding site and the catalytic apparatus in an inter-lobe cleft. Structurally it shares functional and structural similarities with the ATP-grasp fold, which is found in enzymes that catalyse the formation of an amide bond.

The three-dimensional fold of the protein kinase catalytic domain is similar to domains found in several other proteins. These include:

• the catalytic domain of phosphoinositide-3-kinase (PI3K), which phosphorylates phosphoinositides and, as such, is involved in a number of fundamental cellular processes such as apoptosis, proliferation, motility and adhesion [ 2 ]
• choline kinase, which catalyses the ATP-dependent phosphorylation of choline during the biosynthesis of phosphatidylcholine [ 3 ]
• 3',5'-aminoglycoside phosphotransferase type IIIa, a bacterial enzyme that confers resistance to a range of aminoglycoside antibiotics [ 4 ]

This superfamily represents the protein-kinase domain and other related domains that share a similar structure.

1. Structural aspects of protein kinase control-role of conformational flexibility. Pharmacol. Ther. 93, 99-111
2. Structural determinants of phosphoinositide 3-kinase inhibition by wortmannin, LY294002, quercetin, myricetin, and staurosporine. Mol. Cell 6, 909-19
3. The crystal structure of choline kinase reveals a eukaryotic protein kinase fold. Structure 11, 703-13
4. Structural analyses of nucleotide binding to an aminoglycoside phosphotransferase. Biochemistry 40, 8756-64