title: Identification of a cyclin-cdk2 recognition motif present in substrates and p21-like cyclin-dependent kinase inhibitors.
abstract: Understanding how cyclin-cdk complexes recognize their substrates is a central problem in cell cycle biology. We identified an E2F1-derived eight-residue peptide which blocked the binding of cyclin A and E-cdk2 complexes to E2F1 and p21. Short peptides spanning similar sequences in p107, p130, and p21-like cdk inhibitors likewise bound to cyclin A-cdk2 and cyclin E-cdk2. In addition, these peptides promoted formation of stable cyclin A-cdk2 complexes in vitro but inhibited the phosphorylation of the retinoblastoma protein by cyclin A- but not cyclin B-associated kinases. Mutation of the cyclin-cdk2 binding motifs in p107 and E2F1 likewise prevented their phosphorylation by cyclin A-associated kinases in vitro. The cdk inhibitor p21 was found to contain two functional copies of this recognition motif, as determined by in vitro kinase binding/inhibition assays and in vivo growth suppression assays. Thus, these studies have identified a cyclin A- and E-cdk2 substrate recognition motif. Furthermore, these data suggest that p21-like cdk inhibitors function, at least in part, by blocking the interaction of substrates with cyclin-cdk2 complexes.
authors.affiliation: Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02118, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Adams
authors.forename: W R
authors.initials: WR
authors.lastname: Sellers
authors.forename: S K
authors.initials: SK
authors.lastname: Sharma
authors.forename: A D
authors.initials: AD
authors.lastname: Wu
authors.forename: C M
authors.initials: CM
authors.lastname: Nalin
authors.forename: W G
authors.initials: WG
authors.lastname: Kaelin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D042846:CDC2-CDC28 Kinases; D002460:Cell Line; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D006801:Humans; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity / Q000235:genetics
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases