Autoantigenic epitopes on eukaryotic L7.

A H von Mikecz; P H Hemmerich; H H Peter; U Krawinkel

doi:10.1111/j.1365-2249.1995.tb03654.x

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Autoantigenic epitopes on eukaryotic L7.

A H von Mikecz·P H Hemmerich·H H Peter·U Krawinkel

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Abstract

Ribosomal protein L7 has been established recently as a novel autoantigen representing a frequent target for autoantibodies from patients with systemic autoimmune diseases. Up to 75% of systemic lupus erythematosus (SLE) patients and 50% of mixed connective tissue disease (MCTD) and progressive systemic sclerosis (PSS) patients produce antibodies in vitro translated L7 and form immunoprecipitable complexes. In this study the B cell response to protein L7 was investigated with respect to the immunogenic determinants recognized by autoantibodies. Eighteen truncated fragments of protein L7 were generated as recombinant fusions with glutathione-S-transferase and examined by immunoblotting for their reactivity with sera from patients suffering from systemic rheumatic diseases. Anti-L7 antibodies target three major nonoverlapping autoepitopes. Two epitopes reside in the highly conserved C-terminal part of the protein, whereas the N-terminal autoepitope is not conserved during evolution. The N-terminal epitope comprises 24 amino acid residues. Ten amino acid resides of this epitope are shared with the BZIP-like RNA binding domain of protein L7. Autoantibodies recognizing this epitope crossreact with the corresponding region of a L7 homologue, namely ribosomal protein L7 (RPL7) from Dictyostelium discoideum. This indicates that amino acid residues 14VPE...KKR22, which are conserved between humans and fungi, contribute essentially to the formation of autoantibody-autoantigen complexes.

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Amino Acid Sequence Animals Autoantigens Cross Reactions Dictyostelium Epitope Mapping Humans Molecular Sequence Data RNA-Binding Proteins Recombinant Proteins Ribosomal Proteins Sequence Alignment Sequence Homology, Amino Acid Comparative Study Journal Article Research Support, Non-U.S. Gov't

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A H von Mikecz, P H Hemmerich, H H Peter, U Krawinkel. 1995. Autoantigenic epitopes on eukaryotic L7.. https://doi.org/10.1111/j.1365-2249.1995.tb03654.x

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