7QDO

Cryo-EM structure of human monomeric IgM-Fc

7QDO の概要

• エントリーDOI: 10.2210/pdb7qdo/pdb
• EMDBエントリー: 13922
• 分子名称: Isoform 2 of Immunoglobulin heavy constant mu (1 entity in total)
• 機能のキーワード: human monomeric igm-fc, immune system
• 由来する生物種: Homo sapiens (human)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 95374.12

構造登録者

Chen, Q.,Rosenthal, P.,Tolar, P. (登録日: 2021-11-27, 公開日: 2022-10-26, 最終更新日: 2025-07-09)

主引用文献

Chen, Q.,Menon, R.,Calder, L.J.,Tolar, P.,Rosenthal, P.B.
Cryomicroscopy reveals the structural basis for a flexible hinge motion in the immunoglobulin M pentamer.
Nat Commun, 13:6314-6314, 2022

PubMed Abstract: Immunoglobulin M (IgM) is the most ancient of the five isotypes of immunoglobulin (Ig) molecules and serves as the first line of defence against pathogens. Here, we use cryo-EM to image the structure of the human full-length IgM pentamer, revealing antigen binding domains flexibly attached to the asymmetric and rigid core formed by the Cμ4 and Cμ3 constant regions and the J-chain. A hinge is located at the Cμ3/Cμ2 domain interface, allowing Fabs and Cμ2 to pivot as a unit both in-plane and out-of-plane. This motion is different from that observed in IgG and IgA, where the two Fab arms are able to swing independently. A biased orientation of one pair of Fab arms results from asymmetry in the constant domain (Cμ3) at the IgM subunit interacting most extensively with the J-chain. This may influence the multi-valent binding to surface-associated antigens and complement pathway activation. By comparison, the structure of the Fc fragment in the IgM monomer is similar to that of the pentamer, but is more dynamic in the Cμ4 domain.

PubMed: 36274064
DOI: 10.1038/s41467-022-34090-2

実験手法

ELECTRON MICROSCOPY (3.6 Å)