title: Epitopes on proliferating cell nuclear antigen recognized by human lupus autoantibody and murine monoclonal antibody.
abstract: The immune epitopes of proliferating cell nuclear antigen (PCNA), also called cyclin, were analyzed by determining the reactivity between PCNA peptide fragments and anti-PCNA antibodies from lupus patients, murine monoclonal antibody (19A2), and rabbit anti-NH2-terminal peptide antibody. Limited digestion of PCNA/cyclin with Staphylococcus aureus V8 protease resulted in several peptide fragments. Five fragments of 30, 20, 15, 14, and 13 kDa were reactive with rabbit anti-NH2-terminal peptide antibody denoting that they contained the NH2-terminal peptide. The 30- and 20-kDa fragments reacted with 19A2 but the others did not. Lupus sera reacted with 17- and 15-kDa peptide fragments allowing their classification into three groups. Two of eight sera (type A) reacted only with the 17-kDa fragment. Two others (type B) reacted with both the 17- and 15-kDa fragments and the remaining four sera (type C) reacted only with the 15-kDa fragment. The sera reacting with the 15-kDa fragment also reacted with the 20-kDa fragment, but the sera reactive only with the 17-kDa fragment did not, indicating that the 17-kDa fragment was not a degradation product of 20-kDa fragments. The 19A2 epitope resided in the region between 15 and 20 kDa from the NH2 terminus, whereas there was at least one distinct epitope on each 15- and 17-kDa peptide, which were recognized by lupus autoantibodies.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D000939:Epitopes; D006801:Humans; D007163:Immunosorbent Techniques; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D051379:Mice; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D018809:Proliferating Cell Nuclear Antigen
chemical_list: D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D000939:Epitopes; D009687:Nuclear Proteins; D010446:Peptide Fragments; D018809:Proliferating Cell Nuclear Antigen