CCNK (Cyclin K) is a regulatory protein belonging to the cyclin family, which plays critical roles in cell cycle progression and transcriptional regulation. It functions as a partner for cyclin-dependent kinases CDK12 and CDK13. forming complexes essential for modulating RNA polymerase II (RNAP II) activity. These complexes are involved in phosphorylation of the C-terminal domain (CTD) of RNAP II, influencing transcription elongation, mRNA processing, and DNA damage response pathways, particularly homologous recombination repair. CCNK-CDK12/13 also regulates the expression of genes associated with genome stability, including BRCA1 and other DNA repair factors.
Antibodies targeting CCNK are widely used in research to investigate its expression, localization, and interaction networks. They enable detection of CCNK protein levels in various cellular contexts, such as during cell cycle phases or under genotoxic stress. Applications include Western blotting, immunoprecipitation, and immunofluorescence to study its role in transcription-coupled DNA repair mechanisms and cell cycle checkpoints. Dysregulation of CCNK has been implicated in cancers, where genomic instability or altered CDK12/13 activity contributes to tumorigenesis. Thus, CCNK antibodies serve as tools to explore its potential as a biomarker or therapeutic target. Studies using these antibodies have advanced understanding of how transcriptional cyclins coordinate cell proliferation with stress adaptation, highlighting their relevance in cancer biology and drug development.