Takahashi N, Tetaert D, Debuire B, Lin L C, Putnam F W
Proc Natl Acad Sci U S A. 1982 May;79(9):2850-4. doi: 10.1073/pnas.79.9.2850.
We have determined the amino acid sequence of the variable (V) region of the delta heavy (H) chain of human IgD isolated from the plasma of myeloma patient WAH. This V region is unusual in its amino end group (arginine) and in its length (129 residues). The length is due to 10 insertions in the third complementarity-determining region (CDR3). A computer search showed that no reported CDR3-joining region (-JH) sequences are identical and that they appear to be unrelated to the constant (C) region sequences of immunoglobulins. The V region sequence together with our previous results for the C region give the complete sequence of the human delta chain WAH, which has 512 amino acid residues and a Mr congruent to 65,000. The human delta chain has four domains (V, C delta 1, C delta 2, and C delta 3) and a long hinge region; by comparison, the mouse delta chain lacks a continuous segment of 135 residues, including half the hinge region and the entire C delta 2 domain. The human and mouse delta chains also differ in the number, kind, and location of GlcN and GalN glycans and probably in conformation and quaternary structure. These and other considerations suggest that there may be multiple forms of both secreted and membrane-bound IgD that differ in size, structure, and function.
我们已经确定了从骨髓瘤患者WAH血浆中分离出的人IgDδ重链（H链）可变区（V区）的氨基酸序列。该V区在其氨基端基团（精氨酸）和长度（129个残基）方面都很不寻常。其长度归因于在第三个互补决定区（CDR3）中有10个插入片段。计算机检索显示，没有报道的CDR3连接区（-JH）序列是相同的，而且它们似乎与免疫球蛋白的恒定区（C区）序列无关。V区序列连同我们之前关于C区的结果给出了人δ链WAH的完整序列，其有512个氨基酸残基，相对分子质量约为65,000。人δ链有四个结构域（V、Cδ1、Cδ2和Cδ3）以及一个长的铰链区；相比之下，小鼠δ链缺少135个残基的连续片段，包括一半的铰链区和整个Cδ2结构域。人δ链和小鼠δ链在GlcN和GalN聚糖的数量、种类和位置上也有所不同，可能在构象和四级结构上也存在差异。这些以及其他因素表明，可能存在多种形式的分泌型和膜结合型IgD，它们在大小、结构和功能上有所不同。
