"Our goal was to obtain structural information about any
cyclin-CDK complex," says Nikola P.
The CIP/KIP proteins have broad specificity as compared to INK4 proteins for binding and inhibiting the
cyclin-CDK complexes. The activity of cyclin-D-CDK4 is inhibited by these proteins, preventing the Rb phosphorylation during the transition of G1 to S phase and inhibit the activity of cyclin-A-CDK2 and cyclin-E-CDK2 in late G1 and early S phase respectively (Sharpless, 2005).
Functional inactivation of the retinoblastoma protein requires sequential modification by at least two distinct
cyclin-cdk complexes. Mol.
It binds to
cyclin-CDK complexes to inhibit their catalytic activity and induce cell-cycle arrest (Coqueret 2003: Fukuchi et al.
It can stop the cell at any point because it inhibits all of the
cyclin-CDK complexes that nudge the cell through these various stages of division.
Another mechanism that prevents premature entry into the S phase relies on CDK inhibitors (CKIs) that bind onto
cyclin-CDK complexes and disrupt their catalytic centre (Pavletich 1999).