Wienands J, Reth M
Max-Planck Institut für Immunbiologie, Freiburg, Germany.
Nature. 1992 Mar 19;356(6366):246-8. doi: 10.1038/356246a0.
The B-cell antigen receptor of the IgM and IgD class is a multimeric complex consisting of the membrane-bound form of the immunoglobulin molecule and two other proteins, Ig-alpha and Ig-beta. The Ig-alpha and Ig-beta proteins form a disulphide-linked alpha/beta heterodimer and are encoded by the mb-1 (ref 9, 10) and B29 genes, respectively. Surface expression of the membrane-bound IgM molecule requires assembly with the alpha/beta heterodimer. The IgD molecule, however, can be expressed on the cell surface in an alpha/beta-dependent and -independent form. We show here that in the alpha/beta-independent form the IgD molecule is anchored in the plasma membrane through a glycosyl-phosphatidylinositol linker. In the presence of the alpha/beta heterodimer, most of the otherwise glycosyl-phosphatidylinositol-linked IgD molecule is expressed on the cell surface as transmembrane proteins.
IgM和IgD类的B细胞抗原受体是一种多聚体复合物，由免疫球蛋白分子的膜结合形式以及另外两种蛋白质Ig-α和Ig-β组成。Ig-α和Ig-β蛋白形成二硫键连接的α/β异二聚体，分别由mb-1（参考文献9、10）和B29基因编码。膜结合IgM分子的表面表达需要与α/β异二聚体组装。然而，IgD分子可以以α/β依赖和非依赖的形式在细胞表面表达。我们在此表明，在α/β非依赖形式下，IgD分子通过糖基磷脂酰肌醇连接子锚定在质膜中。在存在α/β异二聚体的情况下，大多数原本通过糖基磷脂酰肌醇连接的IgD分子作为跨膜蛋白在细胞表面表达。
