7XT6

Structure of a membrane protein M3

Summary for 7XT6

• Entry DOI: 10.2210/pdb7xt6/pdb
• EMDB information: 33440
• Descriptor: B-cell antigen receptor complex-associated protein alpha chain, Isoform 2 of Immunoglobulin heavy constant mu, B-cell antigen receptor complex-associated protein beta chain, ... (6 entities in total)
• Functional Keywords: membrane protein, immune, immune system
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 4
• Total formula weight: 116575.89

Authors

Ma, X.,Zhu, Y.,Chen, Y.,Huang, Z. (deposition date: 2022-05-16, release date: 2022-08-31, Last modification date: 2024-11-06)

Primary citation

Ma, X.,Zhu, Y.,Chen, Y.,Wang, S.,Yang, D.,Ma, Z.,Zhang, A.,Zhang, F.,Guo, C.,Huang, Z.
Cryo-EM structures of two human B cell receptor isotypes.
Science, 377:880-885, 2022

PubMed Abstract: The B cell receptor (BCR) complex plays a critical role in B cell development and immune responses. The assembly mechanisms underlying the BCR complex remain unknown. We determined the cryo-electron microscopy (cryo-EM) structures of human IgG-BCR and IgM-BCR, which consist of membrane-bound immunoglobulin molecules (mIg) and Igα/β subunits at a 1:1 stoichiometry. Assembly of both BCR complexes involves their extracellular domains, membrane-proximal connection peptides, and transmembrane (TM) helices. The TM helices of mIgG and mIgM share a conserved set of hydrophobic and polar interactions with Igα/β TM helices. By contrast, the IgG-Cγ3 and IgM-Cμ4 domains interact with extracellular Ig-like domains of Igα/β through head-to-tail and side-by-side modes, respectively. This work reveals the structural basis for BCR assembly and provides insights into BCR triggering.

PubMed: 35981028
DOI: 10.1126/science.abo3828

Experimental method

ELECTRON MICROSCOPY (3.63 Å)