Molecular cloning of the liver-specific rat F antigen.
F antigen is a 43-kDa widely conserved liver protein that has been intensively used in studies of immunogenicity and tolerance; two murine allotypes have been identified. Immunization of specific responder inbred strains with liver homogenates from the opposite allotype leads to precipitating antibody and cell-mediated immunity against F. The antibodies produced are autoantibodies as they react equally well with self. We have identified a cDNA clone from rat liver that reacts with alloantisera to F. The fused polypeptide produced by the clone was shown to correspond to F by several experiments. First, alloantisera to F antigen reacted with the cloned fused polypeptide, but not control recombinant clones. Second, mice immunized with the fused polypeptide generate an antibody response that reacts specifically with the 43-kDa protein of mouse liver homogenates and with highly purified F antigen. Finally, both anti-F allosera and sera from mice immunized with the fused polypeptide react with the same 43-kDa liver protein on two-dimensional immunoblots. The nucleotide and deduced amino acid sequence of the clone are presented and the sequence was found to have a significant homology with L28, an Escherichia coli ribosomal protein. The availability of recombinant F antigen will allow definitive questions to be addressed with respect to epitopes and specifically the identification of the T cell epitope which allows for autoimmune responses.
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D000939:Epitopes / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics; D007519:Isoantigens / Q000235:genetics*; D008099:Liver / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C / Q000235:genetics / Q000276:immunology; D008809:Mice, Inbred C3H; D008808:Mice, Inbred CBA / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D051381:Rats; D012269:Ribosomal Proteins / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
D001426:Bacterial Proteins; D000939:Epitopes; D007519:Isoantigens; D012269:Ribosomal Proteins; C030497:liver specific F antigen; D004247:DNA