Anti-CDK8 Antibody Picoband® Fluoro647 Conjugated

Cell division protein kinase 8 is an enzyme that in humans is encoded by the CDK8 gene. It is mapped to 13q12.13. This gene encodes a member of the cyclin-dependent protein kinase (CDK) family. CDK family members are known to be important regulators of cell cycle progression. This kinase and its regulatory subunit, cyclin C, are components of the Mediator transcriptional regulatory complex, involved in both transcriptional activation and repression by phosphorylation of the carboxy-terminal domain of the largest subunit of RNA polymerase II. This kinase regulates transcription by targeting the cyclin-dependent kinase 7 subunits of the general transcription initiation factor IIH, thus providing a link between the Mediator complex and the basal transcription machinery. Multiple pseudogenes of this gene have been identified. Alternative splicing results in multiple transcript variants.

Cyclin-dependent kinase 8; Cell division protein kinase 8; Mediator complex subunit CDK8; Mediator of RNA polymerase II transcription subunit CDK8; Protein kinase K35; CDK8

Predominantly expressed in the liver (PubMed:11099417, PubMed:11452359) . Low expression levels in the small intestine and colon (PubMed:11099417) . Very low levels in other tissues, including brain, heart and spleen (PubMed:11452359) .

Component of the Mediator complex, a coactivator involved in regulated gene transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery. Mediator is recruited to promoters by interactions with regulatory proteins and serves as a scaffold for the assembly of a functional preinitiation complex with RNA polymerase II and the general transcription factors. Phosphorylates the CTD (C-terminal domain) of the large subunit of RNA polymerase II (RNAp II), which may inhibit the formation of a transcription initiation complex. Phosphorylates CCNH leading to down-regulation of the TFIIH complex and transcriptional repression. Recruited through interaction with MAML1 to hyperphosphorylate the intracellular domain of NOTCH, leading to its degradation.

1. Akoulitchev, S., Chuikov, S., Reinberg, D. TFIIH is negatively regulated by cdk8-containing mediator complexes. Nature 407: 102-106, 2000. 2. Donner, A. J., Szostek, S., Hoover, J. M., Espinosa, J. M. CDK8 is a stimulus-specific positive coregulator of p53 target genes. Molec. Cell 27: 121-133, 2007. 3. Firestein, R., Bass, A. J., Kim, S. Y., Dunn, I. F., Silver, S. J., Guney, I., Freed, E., Ligon, A. H., Vena, N., Ogino, S., Chheda, M. G., Tamayo, P., and 16 others. CDK8 is a colorectal cancer oncogene that regulates beta-catenin activity. Nature 455: 547-551, 2008.