title: Characterization of two peptide epitopes on Mdm2 oncoprotein that affect p53 degradation.
abstract: Phosphorylation of Mdm2, in response to DNA damage, resulted in prevention of p53 degradation in the cytoplasm as well as reduction of its binding with monoclonal antibody (mAb) 2A10. Using a 15-mer phage-peptide library, we identified two 2A10-epitopes on human Mdm2 (hdm2): at positions 255-266 (LDSEDYSLSEEG) and 389-400 (QESDDYSQPSTS). Synthetic peptides corresponding to the above sites, inhibit the binding of mAb2A10 to Mdm2 with high (4.5 x 10(-9)M) and moderate affinity (1.1 x 10(-7)M), respectively. Phospho-derivatives of these peptides, and of single human Mdm2 mutations S260D or S395D resulted in a considerable reduction in their binding with mAb2A10. These results provide a molecular explanation for the observation that reactivity of Mdm2 with mAb2A10 is inhibited by phosphorylation.
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel. moshe.balass@weizmann.ac.il
authors.forename: M
authors.initials: M
authors.lastname: Balass
authors.forename: E
authors.initials: E
authors.lastname: Kalef
authors.forename: R
authors.initials: R
authors.lastname: Maya
authors.forename: S
authors.initials: S
authors.lastname: Wilder
authors.forename: M
authors.initials: M
authors.lastname: Oren
authors.forename: E
authors.initials: E
authors.lastname: Katchalski-Katzir
mesh_terms: D000911:Antibodies, Monoclonal / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D018604:Epitope Mapping; D000939:Epitopes; D004926:Escherichia coli / Q000235:genetics; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D009154:Mutation; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D010446:Peptide Fragments; D010455:Peptides; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D014443:Tyrosine; D012694:Serine; D005982:Glutathione Transferase