SLA/LP/tRNP((Ser)Sec) antigen in autoimmune hepatitis: identification of the native protein in human hepatic cell extract.
A diagnostic subgroup of AIH type 1 is characterized by specific serum antibodies against soluble liver protein. The respective autoantigen was named SLA/LP/tRNP((Ser)Sec), after three homologous recombinant polypeptides were isolated from expression gene libraries. We analyzed human cultured liver cells for the human homologue of recombinant SLA/LP/tRNP((Ser)Sec) by antigen purification. In addition, a monoclonal antibody was generated against recombinant SLA-p35, a truncated recombinant SLA-reactive polypeptide. With a positive patient serum, immune affinity chromatography was performed on the 52 kD-SLA main antigenic determinant pre-enriched by ion exchange chromatography. By mass spectrometry, the 52 kD-SLA/LP/tRNP ((Ser)Sec) autoantigen was unambiguously identified in the purification product. The identity of the recombinant SLA-p35 and its human homologue was further confirmed by a specific signal of the anti SLA-p35 monoclonal antibody with purified human SLA/LP/tRNP((Ser)Sec). The 48 kD-SLA species frequently comigrating in SLA-immunoblotting however was not identified by either approach. We conclude that the native counterpart of recombinant tRNP((Ser)(Sec)) indeed is detectable with a molecular weight of 52 kD in soluble liver extract of human cells as the major antigenic component of SLA/LP/tRNP((Ser)Sec).
Volkmann
Martin
M
Labor Prof. Dr. H.-P. Seelig und Kollegen, Karlsruhe, Germany. volkmann@seelig.de
Luithle
Daniel
D
Zentgraf
Hanswalter
H
Schnölzer
Martina
M
Fiedler
Sabine
S
Heid
Hans
H
Schulze-Bergkamen
Andrea
A
Strassburg
Christian P
CP
Gehrke
Sven G
SG
Manns
Michael P
MP
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D001324:Autoantigens / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002457:Cell Extracts; D045744:Cell Line, Tumor; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D019693:Hepatitis, Autoimmune / Q000097:blood / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism*; D022781:Hepatocytes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011994:Recombinant Proteins / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D000911:Antibodies, Monoclonal; D001324:Autoantigens; D002457:Cell Extracts; D010446:Peptide Fragments; D012346:RNA, Transfer, Amino Acyl; D011994:Recombinant Proteins; C112705:selenocysteinyl-tRNA