1. Cyclins: These proteins fluctuate in concentration throughout the cell cycle. They bind to and activate cyclin-dependent kinases (CDKs), which are enzymes that phosphorylate other proteins, triggering various events in the cell cycle. Different cyclins are active at different stages of the cycle, ensuring proper progression through each phase.
2. Cyclin-dependent kinases (CDKs): These enzymes are inactive on their own. They require binding to cyclins to become active. Once activated, CDKs phosphorylate various target proteins, leading to crucial events like DNA replication, chromosome condensation, and nuclear envelope breakdown.
Together, cyclins and CDKs act as a master control system for cell division, ensuring that the correct events occur in the proper order.
