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- Title
Isolation and characterization of cDNA encoding the antigenic protein of the human tRNP<sup>(Ser)Sec</sup> complex recognized by autoantibodies from patients withtype-1 autoimmune hepatitis.
- Authors
Costa, M.; Rodríguez-Sánchez, J. L.; Czaja, A. J.; Gelpí, C.
- Abstract
We previously described autoantibodies against a UGA serine tRNA–protein complex (tRNP(Ser)Sec) in patients with type-1 autoimmune hepatitis [ ] and now define the specificity and frequency of this autoantibody and the DNA sequence encoding the tRNA(Ser)Sec-associated antigenic protein. The presence of anti‐tRNP(Ser)Sec antibodies was highly specific for type-1 autoimmune hepatitis, as 47·5% of patients were positive compared with none of the control subjects. To characterize the antigenic protein(s), we immunoscreened a human cDNA library with anti-tRNP(Ser)Sec-positive sera. Two clones (19 and 13) were isolated. Clone 19 encodes a protein with a predicted molecular mass of 48·8 kD. Clone 13 is a shorter cDNA, almost identical to clone 19, which encodes a 35·9-kD protein. Expression of both cDNAs was accomplished in Escherichia coli as His-tagged recombinant proteins. Antibodies eluted from both purified recombinant proteins were able to immunoprecipitate the tRNA(Ser)Sec from a HeLa S3 cell extract, demonstrating their cross-reactivity with the mammalian antigenic complex. Recent cloning data relating to the target antigen(s) of autoantibodies in autoimmune hepatitis patients that react with a soluble liver antigen (SLA) and a liver-pancreas antigen (LP) have revealed that these two autoantibodies are identical and that the cloned antigen shows 99% amino acid sequence homology with tRNP(Ser)Sec.
- Publication
Clinical & Experimental Immunology, 2000, Vol 121, Issue 2, p364
- ISSN
0009-9104
- Publication type
Academic Journal
- DOI
10.1046/j.1365-2249.2000.01280.x