title: Epstein-Barr virus/complement fragment C3d receptor (CR2) reacts with p53, a cellular antioncogene-encoded membrane phosphoprotein: detection by polyclonal anti-idiotypic anti-CR2 antibodies.
abstract: Epstein-Barr virus and the C3d fragment of the third component of complement are specific extracellular ligands for complement receptor type 2 (CR2). However, intracellular proteins that react specifically with CR2 and are involved in post-membrane signals remain unknown. We recently prepared polyclonal anti-idiotypic anti-CR2 antibodies (Ab2) by using the highly purified CR2 molecule as original immunogen. We showed that Ab2 contained anti-idiotypic specificities that mimicked extracellular domains of CR2 and detected two distinct binding sites on CR2 for its specific extracellular ligands, Epstein-Barr virus and C3d. We postulated that Ab2 might also contain specificities that could mimic intracellular domains of CR2. Here we report that Ab2, which did not react with Raji B-lymphoma cell surface components, detected specifically, among all components solubilized from Raji cell membranes, a single intracellular membrane protein of apparent molecular mass of 53 kDa. This protein was identified as the p53 cellular antioncogene-encoded membrane phosphoprotein by analyzing its antigenic properties with Pab1801, a monoclonal anti-p53 antibody, and by comparing its biochemical properties with those of p53. Additionally, solubilized and purified CR2 bound to solubilized p53 immobilized on Pab1801-Sepharose. p53, like CR2, was localized only in purified plasma membranes and nuclei of Raji cells. These data suggest strongly that p53, a cellular antioncogene-encoded phosphoprotein, reacted specifically with CR2 in Raji membranes. This interaction may represent one of the important steps through which CR2 could be involved in human B-lymphocyte proliferation and transformation.
authors.affiliation: Immunochimie des Antigènes de Membrane et des Interactions Cellulaires, Institut National de la Santé et de la Recherche Médicale, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Barel
authors.forename: A
authors.initials: A
authors.lastname: Fiandino
authors.forename: F
authors.initials: F
authors.lastname: Lyamani
authors.forename: R
authors.initials: R
authors.lastname: Frade
mesh_terms: D000906:Antibodies; D000936:Antigen-Antibody Complex; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D015933:Complement C3d / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D007525:Isoelectric Focusing; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000378:metabolism; D015513:Oncogene Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D009857:Oncogenes; D010750:Phosphoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011951:Receptors, Complement / Q000276:immunology / Q000378:metabolism*; D017464:Receptors, Complement 3d; D016159:Tumor Suppressor Protein p53
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D000944:Antigens, Differentiation, B-Lymphocyte; D007130:Immunoglobulin Idiotypes; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D010750:Phosphoproteins; D011951:Receptors, Complement; D017464:Receptors, Complement 3d; D016159:Tumor Suppressor Protein p53; D015933:Complement C3d