title: Phosducin and monomeric β-actin have common epitope recognized by anti-phosducin antibodies.
abstract: Phosducin family proteins are regulators of cytoplasmic processes. The main function ascribed to phosducin is the binding and sequestration of the β subunit of heterotrimeric G proteins. Phosducin-like protein 1, longer than phosducin by 37 amino-acids, is involved in chaperoning of newly synthesized proteins. β-Actin, a component of the cytoskeleton, participates in cell movement. There is no apparent evolutionary relationship between phosducin and β-actin nor structure similarity. Nevertheless we obtained the polyclonal antibodies named ap33, originally directed against a phosducin-derived peptide (SQSLEEDFEGQATHTGPK), that also recognized β-actin. The epitope on the β-actin molecule was characterized. It is a conformational epitope grouping some of the L-D-F-E-Q-A-T-K amino-acids found in the peptide originally used to obtain the antibodies. The main part of the epitope is localized on the actin-actin interface of polymerized actin, so it is accessible only on monomeric actin. The existence of a common epitope on the molecules of phosducin and β-actin may reflect a topological similarity of a small region of their surfaces.
authors.affiliation: Medical Centre of Postgraduate Education, Department of Biochemistry and Molecular Biology, Marymoncka 99, 01-813 Warsaw, Poland. urszulap@cmkp.edu.pl
authors.forename: Urszula
authors.initials: U
authors.lastname: Piotrowska
authors.forename: Grażyna
authors.initials: G
authors.lastname: Adler
mesh_terms: D000199:Actins / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology* / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D000918:Antibody Specificity / Q000276:immunology; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D000939:Epitopes / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D005136:Eye Proteins / Q000737:chemistry / Q000276:immunology*; D020555:GTP-Binding Protein Regulators / Q000737:chemistry / Q000276:immunology*; D018922:HL-60 Cells; D006801:Humans; D015151:Immunoblotting; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000276:immunology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D000199:Actins; D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000939:Epitopes; D005136:Eye Proteins; D020555:GTP-Binding Protein Regulators; D010750:Phosphoproteins; C065631:phosducin