part of has part transcription factor TFIIH core complex transcription factor TFIIH holo complex cyclin-dependent protein kinase activating kinase holoenzyme complex CAK complex A complex that is capable of kinase activity directed towards the C-terminal Domain (CTD) of the largest subunit of RNA polymerase II and is essential for initiation at RNA polymerase II promoters in vitro. It is composed of the core TFIIH complex and the TFIIK complex. CDK-activating kinase cellular_component GO:0005675 holo TFIIH complex RNA polymerase II, holoenzyme nuclear cyclin-dependent protein kinase holoenzyme complex carboxy-terminal domain protein kinase complex RNA polymerase II transcription regulator complex