cd07868: STKc_CDK8 (this model, PSSM-Id:143373 is obsolete and has been replaced by 270851)
Catalytic domain of the Serine/Threonine Kinase, Cyclin-Dependent protein Kinase 8
Serine/Threonine Kinases (STKs), Cyclin-Dependent protein Kinase 8 (CDK8) subfamily, catalytic (c) domain. STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The CDK8 subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. CDKs belong to a large family of STKs that are regulated by their cognate cyclins. Together, they are involved in the control of cell-cycle progression, transcription, and neuronal function. CDK8 can act as a negative or positive regulator of transcription, depending on the scenario. Together with its regulator, cyclin C, it reversibly associates with the multi-subunit core Mediator complex, a cofactor that is involved in regulating RNA polymerase II (RNAP II)-dependent transcription. CDK8 phosphorylates cyclin H, a subunit of the general transcription factor TFIIH, which results in the inhibition of TFIIH-dependent phosphorylation of the C-terminal domain (CTD) of RNAP II, facilitating the inhibition of transcription. It has also been shown to promote transcription by a mechanism that is likely to involve RNAP II phosphorylation. CDK8 also functions as a stimulus-specific positive coregulator of p53 transcriptional responses.