a Ser/Thr protein kinase of the CMGC group and CDK family. Phosphorylates the C-terminal heptapeptide repeat domain (CTD) of the largest RNA polymerase II subunit RPB1, thereby acting as a key regulator of transcription elongation. Required for RNA splicing, possibly by phosphorylating SRSF1/SF2. Interacts with CCNL1 and CCNL2. Colocalized with nuclear speckles throughout interphase. Has a highly phosphorylated arginine/serine-rich (RS) domain N-terminal to the kinase domain. Chromosomal aberrations involving CDK12 may be a cause gastric cancer. Deletions within 17q12 region producing fusion transcripts with ERBB2, leading to CDK12-ERBB2 fusion leading to trunctated CDK12 protein not in-frame with ERBB2. Three isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Protein type: CDK family; CDK/CRK7 subfamily; CMGC group; CRK7 subfamily; Cell cycle regulation; EC 126.96.36.199; EC 188.8.131.52; Kinase, protein; Motility/polarity/chemotaxis; Protein kinase, CMGC; Protein kinase, Ser/Thr (non-receptor); RNA splicing; Spliceosome