Sequence and expression pattern of J chain in the amphibian, Xenopus laevis
Sequence and expression pattern of J chain in the amphibian, Xenopus laevis
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DOI：
10.1016/s0161-5890(97)82768-x
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发表时间：
1997-10-01
影响因子：
3.6
通讯作者：
Steiner, LA
中科院分区：
文献类型：
--
作者：
Hohman, VS;Stewart, SE;Steiner, LA
我们已经确定了编码J链的cDNA序列，J链是一种与聚合IG相关的多肽辅助分子，来自无尾两栖动物非洲爪蟾（Xenopus laevis）。翻译的多肽由164个氨基酸残基组成，包括信号序列，并且比已经确定J链信号序列的两种哺乳动物物种小鼠和牛中的相应序列稍长。几种哺乳动物物种（人、小鼠、牛和兔）中的J链具有8个Cys残基。在人链中，这些Cys残基中的两个，序列中的第二个和第三个，已被证明与IgM或伊加中的重链形成二硫键;剩余的Cys残基形成链内二硫键。爪蟾J链只含有7个半胱氨酸残基。Ser位于哺乳动物J链中第三个Cys的位置。对从3个月大青蛙的各种器官中分离的RNA进行的北方印迹分析表明，最高水平的表达在肠中。还在脾脏中检测到对应于J链的转录物，在胸腺中检测到非常低的水平。(C)1997 Elsevier Science Ltd.保留所有权利。
We have determined the cDNA sequence encoding J chain, a polypeptide accessory molecule associated with polymeric Ig, from the anuran amphibian, Xenopus laevis (South African clawed frog). The translated polypeptide consists of 164 amino acid residues, including the signal sequence, and is somewhat longer than the corresponding sequence in mouse and cow, the two mammalian species in which the signal sequence of J chain has been determined. J chain in several mammalian species (human, mouse, cow and rabbit) has eight Cys residues. In the human chain, two of these Cys residues, the second and third in the sequence, have been shown to form disulfide bridges to heavy chains in IgM or IgA; the remaining Cys residues form intrachain disulfide bonds. The Xenopus J chain contains only seven of these Cys residues. Ser is found at the position corresponding to the third Cys in mammalian J chains. Northern blot analysis, performed on RNA isolated from various organs of 3-month old frogs, indicated that the highest level of expression was in the intestine. Transcripts corresponding to J chain were also detected in the spleen and at very low levels in the thymus. (C) 1997 Elsevier Science Ltd. All rights reserved.