Cyclin-dependent kinase 12 (CDK12)

Cyclin-dependent kinase which phosphorylates the C- terminal domain (CTD) of the large subunit of RNA polymerase II (POLR2A), thereby acting as a key regulator of transcription elongation. Regulates the expression of genes involved in DNA repair and is required for the maintenance of genomic stability.

Preferentially phosphorylates'Ser-5' in CTD repeats which are currently phosphorylated at'Ser-7', but could also phosphorylate'Ser-2'. Required for RNA splicing, possibly by phosphorylating SRSF1/SF2.