MEDICAL PHYSIOLOGY

Detailed explanation-1: -INK4 proteins (p16INK4a, p15INK4b, p18INK4c and p19INK4d) are specific for the Cdk4 subfamily and interact with the monomeric CDKs. They function by distorting the cyclin interface and the ATP-binding pocket, thus preventing activation of Cdk4 and Cdk6 by D-type cyclins or by CAK [24].

Detailed explanation-2: -Cyclin-dependent kinases (CDKs) are protein kinases characterized by needing a separate subunit-a cyclin-that provides domains essential for enzymatic activity. CDKs play important roles in the control of cell division and modulate transcription in response to several extra-and intracellular cues.

Detailed explanation-3: -As their name suggests, CDKs require the presence of cyclins to become active. Cyclins are a family of proteins that have no enzymatic activity of their own but activate CDKs by binding to them.

Detailed explanation-4: -Two groups of proteins, called cyclins and cyclin-dependent kinases (Cdks), are responsible for the progress of the cell through the various checkpoints. The levels of the four cyclin proteins fluctuate throughout the cell cycle in a predictable pattern.