Cyclins are cell cycle regulatory protein which regulates the catalytic activity of cyclin dependent protein kinase or CDK.From the name cyclin dependent protein kinase it can be concluded that CDK helps in the phosphorylation of key proteins of cell cycle.
The combination of cyclin with CDK helps in the progression of cell from one phase to another.
Such as cyclin A CDK 2 helps also called G1 cyclin CDK helps in progression of cell from G1 to S phase whereas Cyclin B CDK 1 or M cyclin CDK helps in beginning of mitosis phase or M phase of the regulated cell.
