title: Mdmx enhances p53 ubiquitination by altering the substrate preference of the Mdm2 ubiquitin ligase.
abstract: mdm2 and mdmx oncogenes play essential yet non-redundant roles in synergistic inactivation of the tumor suppressor, p53. While Mdm2 inhibits p53 activity mainly by augmenting its ubiquitination, the functional role of Mdmx on p53 ubiquitination remains obscure. In transfected H1299 cells, Mdmx augmented Mdm2-mediated ubiquitination of p53. In in vitro ubiquitination assays, the Mdmx/Mdm2 heteromeric complex, in comparison to the Mdm2 homomer, showed enhanced ubiquitinase activity toward p53 and the reduced auto-ubiquitination of Mdm2. Alteration of the substrate specificity via binding to Mdmx may contribute to efficient ubiquitination and inactivation of p53 by Mdm2.
authors.affiliation: National Cancer Center Research Institute, Early Oncogenesis Research Project, Tokyo, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Okamoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Taya
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakagama
mesh_terms: D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D018797:Cell Cycle Proteins; C482775:MDM4 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2