Cyclin K (CCNK)

Cyclin-K is a member of the transcription cyclin family. These cyclins may regulate transcription through their association with and activation of cyclin-dependent kinases (CDK) that phosphorylate the C-terminal domain (CTD) of the large subunit of RNA polymerase II. The cyclin K gene contains 8 exons. Northern blot analysis indicated that the 2.3-kb cyclin K transcript was present in all human adult tissues tested, with the highest level in testis. Additional 2.9- and 1.4-kb mRNAs were also detected in some tissues. Using in situ hybridization, the authors found that cyclin K mRNA is highly expressed in the developing germ cells of adult mouse testis and ovary. The predicted 357-amino acid cyclin K protein shares 99% and 22% identity with mouse cyclin K and human cyclin C, respectively.