title: Mutational effects on the p16INK4a tumor suppressor protein.
abstract: Several point mutations of p16INK4a were studied by site-specific mutagenesis and functional analysis to assess the effects of these mutations on the function of the protein. These mutations were reported in several malignancies. Three deletional mutants of p16INK4a were also analyzed to reveal the relationship between p16INK4a and p15INK4b and to test the importance of the ankyrin repeats observed in both proteins. We studied the activity of these mutants using the yeast two-hybrid system and an in vitro kinase assay. Our results suggest that point mutations in the conserved ankyrin consensus affect the activity of p16INK4a. However, not all of the point mutations observed in tumors have a detectable effect on the activity. The COOH-terminal region of p16INK4a is not required for the protein to bind and to inhibit CDK4, but the deletion of the 4th ankyrin repeat abolished the activity completely.
authors.affiliation: Division of Hematology/Oncology, University of California, Los Angeles 90048, USA.
authors.forename: R
authors.initials: R
authors.lastname: Yang
authors.forename: A F
authors.initials: AF
authors.lastname: Gombart
authors.forename: M
authors.initials: M
authors.lastname: Serrano
authors.forename: H P
authors.initials: HP
authors.lastname: Koeffler
mesh_terms: D000595:Amino Acid Sequence; D017487:Ankyrins / Q000737:chemistry; D002352:Carrier Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D003001:Cloning, Molecular; D016384:Consensus Sequence; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004926:Escherichia coli / Q000254:growth & development; D016147:Genes, Tumor Suppressor; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009369:Neoplasms / Q000235:genetics; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
chemical_list: D017487:Ankyrins; D002352:Carrier Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins