CDKcyklinpar

CDKcyklinpar, often referred to as cyclin-dependent kinase-cyclin complexes, are crucial regulators of the eukaryotic cell cycle. These complexes are composed of two distinct protein subunits: a catalytic subunit, the cyclin-dependent kinase (CDK), and a regulatory subunit, a cyclin. The activity of CDKs is tightly controlled by their association with cyclins, which are expressed and degraded in a cell cycle-dependent manner.

Different cyclin-CDK pairs are responsible for driving specific phases of the cell cycle. For example, Cyclin D-CDK4/6 complexes are important for progression through the G1 phase, preparing the cell for DNA replication. Cyclin E-CDK2 complexes are involved in the transition from G1 to S phase, initiating DNA synthesis. Cyclin A-CDK2 and Cyclin A-CDK1 complexes play roles in both S phase and G2 phase, ensuring proper DNA replication and preparation for mitosis. Finally, Cyclin B-CDK1 (also known as MPF, maturation-promoting factor) is the key regulator of entry into mitosis (M phase).

The assembly of these complexes is a prerequisite for their enzymatic activity. Once formed, CDKcyklinpar phosphorylate a wide range of substrate proteins, including transcription factors, enzymes, and structural proteins. These phosphorylation events trigger the downstream molecular events that drive cell cycle progression, such as the activation of DNA replication machinery, chromosome condensation, and the formation of the mitotic spindle. The precise regulation of CDKcyklinpar activity is essential for maintaining genomic stability and preventing uncontrolled cell proliferation, making them critical targets for cancer therapy.