title: Identification of human and mouse p19, a novel CDK4 and CDK6 inhibitor with homology to p16ink4.
abstract: The cell cycle in mammalian cells is regulated by a series of cyclins and cyclin-dependent kinases (CDKs). The G1/S checkpoint is mainly dictated by the kinase activities of the cyclin D-CDK4 and/or cyclin D-CDK6 complex and the cyclin E-CDK2 complex. These G1 kinases can in turn be regulated by cell cycle inhibitors, which may cause the cells to arrest at the G1 phase. In T-cell hybridomas, addition of anti-T-cell receptor antibody results not only in G1 arrest but also in apoptosis. In searching for a protein(s) which might interact with Nur77, an orphan steroid receptor required for activation-induced apoptosis of T-cell hybridomas, we have cloned a novel human and mouse CDK inhibitor, p19. The deduced p19 amino acid sequence consists of four ankyrin repeats with 48% identity to p16. The human p19 gene is located on chromosome 19p13, distinct from the positions of p18, p16, and p15. Its mRNA is expressed in all cell types examined. The p19 fusion protein can associate in vitro with CDK4 but not with CDK2, CDC2, or cyclin A, B, E, or D1 to D3. Addition of p19 protein can lead to inhibition of the in vitro kinase activity of cyclin D-CDK4 but not that of cyclin E-CDK2. In T-cell hybridoma DO11.10, p19 was found in association with CDK4 and CDK6 in vivo, although its association with Nur77 is not clear at this point. Thus, p19 is a novel CDK inhibitor which may play a role in the cell cycle regulation of T cells.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.
authors.forename: F K
authors.initials: FK
authors.lastname: Chan
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Cheng
authors.forename: D N
authors.initials: DN
authors.lastname: Shapiro
authors.forename: A
authors.initials: A
authors.lastname: Winoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D002453:Cell Cycle; D002874:Chromosome Mapping; D002888:Chromosomes, Human, Pair 19; D003001:Cloning, Molecular; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D019941:Cyclin-Dependent Kinase Inhibitor p16; D018844:Cyclin-Dependent Kinases; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D011518:Proto-Oncogene Proteins; D017346:Protein Serine-Threonine Kinases; C495900:CDK4 protein, human; C495911:CDK6 protein, human; C495902:Cdk4 protein, mouse; C495912:Cdk6 protein, mouse; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases