Kikutani H, Sitia R, Good R A, Stavnezer J
Proc Natl Acad Sci U S A. 1981 Oct;78(10):6436-40. doi: 10.1073/pnas.78.10.6436.
We have compared the synthesis and processing of immunoglobulin alpha chains in two murine cell lines, a B cell lymphoma that expresses membrane-bound IgA and a hybridoma that secretes IgA. Results of biosynthetic labeling experiments demonstrated that membrane-bound and secreted alpha chains have two distinct intracellular precursors, of different molecular weights and isoelectric points. RNAs from both of these cell lines direct the synthesis in vitro of two alpha polypeptides of Mr 59,000 and 62,000, the larger one being the precursor for membrane-bound alpha chain and the smaller one being the precursor for secreted alpha chain. These cell lines each contain three RNAs, 1.7, 2.1, and 3.1 kilobases in length, which hybridize with cDNA for the alpha constant region and which are present in different concentrations. Our results suggest that the smallest RNA encodes the secreted alpha chain and one or both of the larger RNAs encode(s) the membrane-bound alpha chain.
我们比较了两种鼠细胞系中免疫球蛋白α链的合成与加工过程，一种是表达膜结合型IgA的B细胞淋巴瘤，另一种是分泌IgA的杂交瘤。生物合成标记实验结果表明，膜结合型和分泌型α链有两种不同的细胞内前体，分子量和等电点不同。来自这两种细胞系的RNA在体外指导合成两种分子量分别为59,000和62,000的α多肽，较大的一种是膜结合型α链的前体，较小的一种是分泌型α链的前体。这些细胞系各自含有三种长度分别为1.7、2.1和3.1千碱基的RNA，它们与α恒定区的cDNA杂交，且浓度不同。我们的结果表明，最小的RNA编码分泌型α链，而较大的一种或两种RNA编码膜结合型α链。
