Cell division protein kinase 9 Cyclin-dependent kinase 9 Serine/threonine-protein kinase PITALRE Cell division cycle 2-like protein kinase 4 C-2K

CDK9 (PITALRE) (also known as cyclin-dependent kinase 9, Serine/threonine-protein kinase PITALRE, C-2K and Cell division cycle 2-like protein kinase 4) is a member of the cyclin- dependent protein kinase (CDK) family. CDK family members are highly similar to the gene products of S. cerevisiae cdc28 and S. pombe cdc2 and are known as important cell cycle regulators. CDK9 (PITALRE) interacts with a conserved domain in the TRAF-C region of the tumor necrosis factor signal transducer TRAF2. This kinase was also found to be a component of the multiprotein complex TAK/P-TEFb, which is an elongation factor for RNA polymerase II-directed transcription and functions by phosphorylating the C-terminal domain of the largest subunit of RNA polymerase II. This protein forms a complex with, and is regulated by, its regulatory subunit, cyclin T or cyclin K. HIV-1 Tat protein.