Effects of phosphorylation by CAK on cyclin binding by CDC2 and CDK2.
AUTOR(ES)
Desai, D
RESUMO
The cyclin-dependent protein kinases (CDKs) are activated by association with cyclins and by phosphorylation at a conserved threonine residue by the CDK-activating kinase (CAK). We have studied the binding of various human CDK and cyclin subunits in vitro, using purified proteins derived from baculovirus-infected insect cells. We find that most CDK-cyclin complexes known to exist in human cells (CDC2-cyclin B, CDK2-cyclin A, and CDK2-cyclin E) form with high affinity in the absence of phosphorylation or other cellular components. One complex (CDC2-cyclin A) forms with high affinity only after CAK-mediated phosphorylation of CDC2 at the activating threonine residue. CDC2 does not bind with high affinity to cyclin E in vitro, even after phosphorylation of the CDC2 subunit. Thus, phosphorylation is of varying importance in the formation of high-affinity CDK-cyclin complexes.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=231966Documentos Relacionados
- Phosphorylation of the retinoblastoma protein by cdk2.
- cdc2 phosphorylation is required for its interaction with cyclin.
- Phosphorylation and activation of the Xenopus Cdc25 phosphatase in the absence of Cdc2 and Cdk2 kinase activity.
- A three-dimensional model of the Cdc2 protein kinase: localization of cyclin- and Suc1-binding regions and phosphorylation sites.
- CAK-independent Activation of CDK6 by a Viral Cyclin