The phosphorylated form of CDK7, the CDK-activating kinase MNAT1 and cyclin H associate in a trimer referred to as CAK (Cyclin-dependent kinase Activating Kinase) (Viallard et al. 2001). The complex phosphorylates and activates the kinases CDK1, CDK2, CDK4 and CDK6. CAK seems to intervene throughout the cycle (Coqueret 2002; Vermeulen et al. 2003). |
