van Noesel C J, van Lier R A, Cordell J L, Tse A G, van Schijndel G M, de Vries E F, Mason D Y, Borst J
Central Laboratory of The Netherlands Red Cross Blood Transfusion Service, Amsterdam.
J Immunol. 1991 Jun 1;146(11):3881-8.
7/8embrane IgM (mIgM) on human B lymphocytes is noncovalently associated with a disulfide-linked dimer that contains phosphoproteins of 47 and 37 kDa. In this study, the biochemical properties and the identity of these Ag receptor-associated components have been addressed. Both subunits carry N-linked carbohydrate groups. After deglycosylation, the 47-kDa and 37-kDa proteins have similar molecular masses, of about 23 kDa, and relatively acidic but different isoelectric points. The accumulated data, together with a previously performed comparison of tryptic peptides, suggest that the two components are structurally distinct and possibly encoded by different genes. Indeed, a mAb, raised against a synthetic peptide that was made on the basis of the published carboxyl-terminal amino acid sequence of the human mb-1 gene product, specifically reacted with the 47-kDa but not the 37-kDa subunit. None of the established B cell-specific mAb characterized in the Fourth International Workshop on Leukocyte Antigens, including CD24, CD37, and CD72, detect the mIgM-linked heterodimer, which makes it a newly defined human B cell Ag.
人B淋巴细胞上7/8的膜免疫球蛋白M（mIgM）与一个二硫键连接的二聚体非共价结合，该二聚体包含47 kDa和37 kDa的磷蛋白。在本研究中，已对这些与抗原受体相关成分的生化特性和身份进行了研究。两个亚基都带有N-连接的碳水化合物基团。去糖基化后，47 kDa和37 kDa的蛋白质具有相似的分子量，约为23 kDa，且相对呈酸性，但等电点不同。积累的数据以及先前对胰蛋白酶肽段的比较表明，这两个成分在结构上是不同的，可能由不同的基因编码。实际上，一种针对基于人mb-1基因产物已发表的羧基末端氨基酸序列合成的肽段产生的单克隆抗体，特异性地与47 kDa亚基反应，而不与37 kDa亚基反应。在第四届白细胞抗原国际研讨会上鉴定的已确立的B细胞特异性单克隆抗体，包括CD24、CD37和CD72，均未检测到与mIgM连接的异二聚体，这使其成为一种新定义的人B细胞抗原。
