Amino acid sequence of heavy chain from Xenopus laevis IgM deduced from cDNA sequence: implications for evolution of immunoglobulin domains.
Amino acid sequence of heavy chain from Xenopus laevis IgM deduced from cDNA sequence: implications for evolution of immunoglobulin domains.
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DOI：
10.1073/pnas.85.7.2245
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发表时间：
1988-04
影响因子：
11.1
通讯作者：
Joseph Schwager;Carole A. Mikoryak;Lisa A. Steiner
中科院分区：
文献类型：
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作者：
Joseph Schwager;Carole A. Mikoryak;Lisa A. Steiner
目前对免疫球蛋白进化的理解几乎完全来自对少数哺乳动物物种的研究。为了获得有关非洲爪蟾免疫球蛋白基因的信息，在表达载体λ gt 11中制备来自该物种的有丝分裂原刺激的脾细胞的cDNA文库。在筛选的约等于50，000个克隆中，发现18个表达IgM表位。其中之一，λ XIg 14，与来自脾细胞的约等于2个核糖核酸酶的RNA杂交。该克隆的插入片段似乎编码可变区和部分mu恒定区;另一个克隆λ XIg 8的插入片段似乎编码可变区和完整的mu恒定区。两个插入片段均含有对应于编码重链可变区的三个基因区段（VH、DH和JH）的序列。由λ XIg 8编码的重链恒定区（CH）具有C μ的特征性特征，包括四结构域结构和羧基末端尾。两个μ链肽的氨基酸序列与cDNA序列一致。相应的非洲爪蟾和小鼠C mu结构域之间的氨基酸序列的同一性范围为31至47%。C μ结构域在它们的序列类似于其他免疫球蛋白的序列的程度上不同，这与先前的免疫球蛋白结构域具有独立进化历史的建议一致。
Present understanding of the evolution of immunoglobulins is derived almost entirely from studies of a few mammalian species. To obtain information about immunoglobulin genes in Xenopus laevis, a cDNA library was prepared in the expression vector lambda gt11 from mitogen-stimulated splenocytes of this species. Of approximately equal to 50,000 clones screened, 18 were found to express IgM epitopes. One of these, lambda XIg14, hybridized with RNA of RNA of approximately equal to 2 kilobases from splenocytes. The insert of this clone appears to encode a variable region and part of a mu constant region; that of another clone, lambda XIg8, appears to encode a variable region and a complete mu constant region. Both inserts contain sequence corresponding to the three gene segments (VH, DH, and JH) that encode heavy-chain variable regions. The heavy-chain constant region (CH) encoded by lambda XIg8 has the characteristic features of C mu, including a four-domain structure and a carboxyl-terminal tail. The amino acid sequences of two mu-chain peptides agree with the cDNA sequence. The identity in amino acid sequence between the corresponding Xenopus and mouse C mu domains ranges from 31 to 47%. The C mu domains vary in the extent to which their sequences resemble the sequences of other immunoglobulins, consistent with previous suggestions that the immunoglobulin domains have an independent evolutionary history.