A serial switch for kinase activation: Double-phosphorylated Cdk7 turns on full activity! The Cyclin-dependent kinase 7 has two functions, it activates other CDKs to turn on the cell cycle and it phosphorylates RNA polymerase II to initiate transcription. Robert discovered that the first function does not require Cdk7 phosphorylation whereas the second function is fully boosted by the sequential phosphorylation of two sites in the kinase T loop. Read the full story here
