3 or 4 cGMP molecules must bind to each channel in order to open it; because of this cooperative allosteric interaction, channel opening is very sensitive to small changes in cGMP levels.

TLS Online TPP Program

#Id: 8617

#XL - T Zoology

Wee1 kinase Inhibits CDKs in all organisms

TLS Online TPP Program

#Id: 8618

#XL - T Zoology

Cdc25 phosphatase Activates CDKs in fission yeast

TLS Online TPP Program

#Id: 8619

#XL - T Zoology

INK4s

bind to CDK4 and CDK6 monomers, blocking their interaction with cyclin D

TLS Online TPP Program

#Id: 8620

#XL - T Zoology

A second class of CKIs found in metazoan cells is the Cip/Kip family of CKIs, consists of three proteins—p21CIP, p27KIP1, and p57KIP2. 

TLS Online TPP Program

#Id: 8621

#XL - T Zoology

The Cip/Kip family members bind to cyclin-bound CDKs and block the activity of cyclin D-, E-, A-, and B-containing complexes.

TLS Online TPP Program

#Id: 8622

#XL - T Zoology

Cyclins are degraded through the action of two different E3-ligases:

1. SCF (Skp1, Cullin, and F-box proteins) 

2. APC/C or cyclosome