Hasegawa H, Uchiumi T, Sato T, Arakawa M, Kominami R
Niigata University School of Medicine, Japan.
Arthritis Rheum. 1998 Jun;41(6):1040-6. doi: 10.1002/1529-0131(199806)41:6<1040::AID-ART10>3.0.CO;2-2.
Cross-reactivity of anti-Sm autoantibodies with a certain ribosomal protein has been reported previously. The present study was undertaken to identify the anti-Sm-reactive ribosomal protein, and to characterize the cross-reactive epitope.
Two-dimensional gel electrophoresis followed by immunoblotting was used to identify the ribosomal protein (S10) which was reactive with the Y12 anti-Sm monoclonal antibody (MAb). Human anti-Sm antibodies were also tested for cross-reactivity with the Sm-B/B', Sm-D, and isolated S10 proteins by immunoblotting. Epitope analysis was performed by immunoprecipitation of in vitro-translated products of the recombinant S10 and its various mutants.
The Y12 MAb and the affinity-purified human anti-Sm autoantibodies cross-reacted with ribosomal S10 protein. Reactivity of the Y12 MAb with S10 protein was abolished by deletion of 19 amino acids at the carboxyl-terminus of S10, containing the Gly-Arg-Gly sequence motif shared by Sm-B/B' and Sm-D (D1 and D3). Replacements of Arg-158 with Gly and of Arg-158/Arg-160 with Gly/Gly at the carboxyl-terminal 157-Gly-Arg-Gly-Arg-Gly region disrupted the Y12 MAb recognition.
At least a part of human anti-Sm antibodies and Y12 MAb show cross-reactivity among Sm-B/B', Sm-D, and ribosomal protein S10. The carboxyl-terminal Gly-Arg-Gly region of S10 protein is involved in constructing the cross-reactive epitope. This demonstrates that a common structural feature is shared by the ribosomal protein and the small nuclear RNP proteins.
先前已有报道抗Sm自身抗体与某种核糖体蛋白存在交叉反应。本研究旨在鉴定与抗Sm反应的核糖体蛋白，并对交叉反应表位进行特征分析。
采用二维凝胶电泳及免疫印迹法鉴定与Y12抗Sm单克隆抗体（MAb）反应的核糖体蛋白（S10）。还通过免疫印迹法检测人抗Sm抗体与Sm-B/B'、Sm-D及分离的S10蛋白的交叉反应。通过对重组S10及其各种突变体的体外翻译产物进行免疫沉淀来进行表位分析。
Y12 MAb和亲和纯化的人抗Sm自身抗体与核糖体S10蛋白发生交叉反应。S10羧基末端缺失19个氨基酸（包含Sm-B/B'和Sm-D共有的Gly-Arg-Gly序列基序）后，Y12 MAb与S10蛋白的反应性消失。在羧基末端157-Gly-Arg-Gly-Arg-Gly区域，将Arg-158替换为Gly以及将Arg-158/Arg-160替换为Gly/Gly会破坏Y12 MAb的识别。
至少一部分人抗Sm抗体和Y12 MAb在Sm-B/B'、Sm-D和核糖体蛋白S10之间表现出交叉反应。S10蛋白的羧基末端Gly-Arg-Gly区域参与构建交叉反应表位。这表明核糖体蛋白和小核核糖核蛋白具有共同的结构特征。
