title: Monoclonal antibody Y13-259 recognizes an epitope of the p21 ras molecule not directly involved in the GTP-binding activity of the protein.
abstract: The p21 products of ras proto-oncogenes are GTP-binding proteins with associated GTPase activity. Recent studies have indicated that ras p21 may be required for the initiation of normal cell DNA synthesis, since microinjection of a monoclonal antibody, Y13-259, blocks serum stimulation of DNA synthesis in quiescent cell cultures (L. S. Mulcahy, M.R. Smith, and D. W. Stacey, Nature [London] 313:241-243, 1985). We localized the structural domain within the p21 molecule recognized by the Y13-259 monoclonal antibody. By analysis of a series of bacterially expressed p21 deletion mutants, the monoclonal antibody was found to interact with a region between positions 70 and 89 in the p21 amino acid sequence. By comparison of the coding sequences of different p21 proteins recognized by this monoclonal antibody, a highly conserved amino acid region between positions 70 and 81 was found to be the most likely site for the epitope detected by the Y13-259 antibody. This monoclonal antibody was further shown not to interfere directly with in vitro biochemical functions of the molecule, including GTP binding, GTPase, and autokinase activities.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D006224:Cricetinae; D000939:Epitopes / Q000032:analysis*; D004926:Escherichia coli / Q000235:genetics; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015689:Oncogene Protein p21(ras); D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids; D011519:Proto-Oncogenes; D009053:Sarcoma Viruses, Murine / Q000235:genetics*; D013045:Species Specificity
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D009856:Oncogene Proteins, Viral; D019204:GTP-Binding Proteins; D015689:Oncogene Protein p21(ras)