Differential interaction of the cyclin-dependent kinase (Cdk) inhibitor p27Kip1 with cyclin A-Cdk2 and cyclin D2-Cdk4.
Although p27(Kip1) has been considered a general inhibitor of G1 and S phase cyclin-dependent kinases, we report that the interaction of p27 with two such kinases, cyclin A-Cdk2 and cyclin D-Cdk4, is different. In Mv1Lu cells containing a p27 inducible system, a 6-fold increase over the basal p27 level completely inhibited Cdk2 and cell cycle progression. In contrast, the same or a larger increase in p27 levels did not inhibit Cdk4 or its homologue Cdk6, despite extensive binding to these kinases. A p27-cyclin A-Cdk2 complex formed in vitro was essentially inactive, whereas a p27-cyclin D2-Cdk4 complex was active as a retinoblastoma kinase and served as a substrate for the Cdk-activating kinase Cak. High concentrations of p27 inhibited cyclin D2-Cdk4, apparently by conversion of active complexes into inactive ones by the binding of additional p27 molecules. In contrast to their differential interaction, cyclin A-Cdk2 and cyclin D2-Cdk4 were similarly inhibited by bound p21(Cip1/Waf1). Roles of cyclin A-Cdk2 as a p27 target and cyclin D2-Cdk4 as a p27 reservoir may result from the differential ability of bound p27 to inhibit the kinase subunit in these complexes.
Blain
S W
SW
Cell Biology Program and Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Montalvo
E
E
Massagué
J
J
D000818:Animals; D042846:CDC2-CDC28 Kinases; D018797:Cell Cycle Proteins; D002460:Cell Line; D019925:Cyclin A / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008907:Mink; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D019925:Cyclin A; D016213:Cyclins; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D047428:Protein Kinase Inhibitors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases