Structural insights into immunoglobulin M

• DOI: 10.1126/science.aaz5425
• Publication Date: 2020-02-07T00:09:24Z
• Authors: Yaxin Li; Guopeng Wang; Ningning Li; Yuxin Wang; Qinyu Zhu; Huarui Chu; Wenjun Wu; Ying Tan; Feng Yu; Xiao-Dong Su; Ning Gao; Junyu Xiao
• Keywords: Pentamer; Polymeric immunoglobulin receptor; Ectodomain; Fragment crystallizable region; Immunoglobulin M; Immunoglobulin domain; J chain; Immunoglobulin A

Immunoglobulin M (IgM) plays a pivotal role in both humoral and mucosal immunity. Its assembly transport depend on the joining chain (J-chain) polymeric immunoglobulin receptor (pIgR), but underlying molecular mechanisms of these processes are unclear. We report cryo-electron microscopy structure Fc region human IgM complex with J-chain pIgR ectodomain. The IgM-Fc pentamer is formed asymmetrically, resembling hexagon missing triangle. tailpieces pack into an amyloid-like to stabilize pentamer. caps tailpiece bridges interaction between receptor, which undergoes large conformational change engage IgM-J complex. These results provide structural basis for function IgM.