Structural insights into immunoglobulin M
Structural insights into immunoglobulin M
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免疫球蛋白M的结构解析
DOI：
10.1126/science.aaz5425
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发表时间：
2020-02-28
期刊：
影响因子：
56.9
通讯作者：
Xiao, Junyu
中科院分区：
文献类型：
--
作者：
Li, Yaxin;Wang, Guopeng;Xiao, Junyu
免疫球蛋白M（IgM）在体液免疫和粘膜免疫中起着关键作用。其组装和转运依赖于连接链（J链）和多聚免疫球蛋白受体（pIgR），但这些过程的潜在分子机制尚不清楚。我们报告了人IgM Fc区与J链和pIgR胞外域复合物的冷冻电镜结构。IgM-Fc五聚体不对称形成，类似于缺少三角形的六边形。IgM-Fc的尾片段包装成淀粉样结构以稳定五聚体。J链覆盖尾片段组装并桥接IgM-Fc与多聚免疫球蛋白受体之间的相互作用，其经历大的构象变化以接合IgM-J复合物。这些结果为IgM的功能提供了结构基础。
Immunoglobulin M (IgM) plays a pivotal role in both humoral and mucosal immunity. Its assembly and transport depend on the joining chain (J-chain) and the polymeric immunoglobulin receptor (pIgR), but the underlying molecular mechanisms of these processes are unclear. We report a cryo-electron microscopy structure of the Fc region of human IgM in complex with the J-chain and pIgR ectodomain. The IgM-Fc pentamer is formed asymmetrically, resembling a hexagon with a missing triangle. The tailpieces of IgM-Fc pack into an amyloid-like structure to stabilize the pentamer. The J-chain caps the tailpiece assembly and bridges the interaction between IgM-Fc and the polymeric immunoglobulin receptor, which undergoes a large conformational change to engage the IgM-J complex. These results provide a structural basis for the function of IgM.