背景资料:CDK7 is a protein-serine/threonine kinase. CDK7 has been identified as the mammalian homolog of MO15, a protein kinase demonstrated in starfish and Xenopus. The regulatory subunit is a novel cyclin (cyclin H) and is required for activation of CDK7. Like other Cdks, CDK7 contains a conserved threonine residue required for full activity; mutation of this residue severely reduces CAK activity.