Singer P A, Singer H H, Williamson A R
Nature. 1980 May 29;285(5763):294-300. doi: 10.1038/285294a0.
Biosynthetic studies in the presence of an inhibitor of glycosylation indicate that individual human lymphoma-derived cell lines can synthesize both membrne receptor and presumptive secretory forms of IgM mu chains. The receptor form has a larger polypeptide chain than the secretory form and possesses a different C-terminus, but similar N-terminus, consistent with the presence of a C-terminal hydrophobic "tail" for integral membrane binding. Messenger RNA isolated from these cells directs the synthesis of both forms of mu chains in a wheat germ translation system, indicating the presence of independent mRNAs for each form. It is proposed that the synthetic pathways for receptor and secretory IgM diverge at the post-transcriptional level, possibly by differential RNA splicing to give mRNA molecules with or without a translatable "tail" segment.
在存在糖基化抑制剂的情况下进行的生物合成研究表明，源自人类淋巴瘤的各个细胞系能够合成膜受体形式和假定的分泌形式的IgM μ链。受体形式的多肽链比分泌形式的大，并且具有不同的C末端，但N末端相似，这与存在用于整合膜结合的C末端疏水“尾巴”一致。从这些细胞中分离出的信使RNA在小麦胚芽翻译系统中指导两种形式的μ链的合成，表明每种形式都存在独立的mRNA。有人提出，受体和分泌型IgM的合成途径在转录后水平上发生分歧，可能是通过差异RNA剪接产生具有或不具有可翻译“尾巴”片段的mRNA分子。
