Molecular components of the B cell antigen receptor complex of class IgD differ partly from those of IgM.
Molecular components of the B cell antigen receptor complex of class IgD differ partly from those of IgM.
复制标题
IgD 类 B 细胞抗原受体复合物的分子成分部分不同于 IgM 类。
作者：
J. Wienands;J. Hombach;Andreas Radbruch;C. Riesterer;M. Reth
两类免疫球蛋白IgM和IgD作为抗原受体存在于成熟B淋巴细胞表面。我们在这里显示，IgD分子在B细胞膜中与异源二聚体非共价结合，该异源二聚体分别由35 kd（IgD-α）和39 kd（IG-β）的两种蛋白质组成。在表达IgD的骨髓瘤J558 L delta m中未发现这两种新蛋白，其无法将IgD抗原受体带到细胞表面。然而，在该骨髓瘤的表面IgD阳性变异系中，膜结合IgD分子与异二聚体相关，表明表面IgD表达需要形成抗原受体复合物。我们进一步证明了IgD相关的异源二聚体与IgM抗原受体部分不同，并且其与重链的结合仅需要最后一个恒定结构域和Δ m链的跨膜部分的存在。
Two classes of immunoglobulin, IgM and IgD, are present as antigen receptors on the surface of mature B lymphocytes. We show here that IgD molecules are noncovalently associated in the B cell membrane with a heterodimer consisting of two proteins of 35 kd (IgD‐alpha) and 39 kd (Ig‐beta), respectively. The two novel proteins are not found in the IgD‐expressing myeloma J558L delta m, which fails to bring IgD antigen receptor onto the cell surface. In a surface IgD positive variant line of this myeloma, however, membrane‐bound IgD molecules are associated with the heterodimer, suggesting that the formation of an antigen receptor complex is required for surface IgD expression. We further demonstrate that the IgD‐associated heterodimer differs partly from that of the IgM antigen receptor and that its binding to the heavy chain only requires the presence of the last constant domain and the transmembrane part of the delta m chain.