Fluorescent protein biosensor for probing CDK/cyclin activity in vitro and in living cells.

Cyclin-dependent kinases (CDKs) play an essential role in the coordination of cell cycle progression and transcriptional regulation; hyperactivation is associated with cancer. However there are few means of measuring their activity in a physiological context or their inhibition in response to therapeutics. To this aim we engineered a modular fluorescent protein biosensor that reports on phosphorylation by CDK/cyclins through real-time changes in fluorescence intensity.