fig2

Figure 2. CDKs and their function in RNA PolII transcription. CDKs 7 and 9 are involved in RNA polymerase II activity by directly phosphorylating CTD and thus control the generation of mRNA transcripts. CDK7-CycH-Mat1 complex is under control of CDK8-CycC complex, which acts as its inhibitor. CDK8-CycC complex also prevents binding of RNA PolII to promoter DNA region by its phosphorylation. CDK7-CycH-Mat1 complex phosphorylates RNA PolII CTD domain and enables transcription initiation. Further phosphorylation with CDK9-CycT leads to transcription elongation and mRNA production. Single letters stand for cyclins, for instance T is cyclin T. Pol II: RNA polymerase II; P: phosphatidyl group; CDK: cyclin-dependent kinase; CTD: carboxy-terminal domain; mRNA: messenger RNA