Effects of phosphorylation by CAK on cyclin binding by CDC2 and CDK2.
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.
Mesh Terms:
CDC2 Protein Kinase, CDC2-CDC28 Kinases, Chromatography, Gel, Cyclin-Dependent Kinase 2, Cyclin-Dependent Kinases, Cyclins, Humans, Mutagenesis, Site-Directed, Phosphorylation, Protamine Kinase, Protein-Serine-Threonine Kinases, Recombinant Proteins, Structure-Activity Relationship
CDC2 Protein Kinase, CDC2-CDC28 Kinases, Chromatography, Gel, Cyclin-Dependent Kinase 2, Cyclin-Dependent Kinases, Cyclins, Humans, Mutagenesis, Site-Directed, Phosphorylation, Protamine Kinase, Protein-Serine-Threonine Kinases, Recombinant Proteins, Structure-Activity Relationship
Mol. Cell. Biol.
Date: Jan. 01, 1995
PubMed ID: 7799941
View in: Pubmed Google Scholar
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