Rxivist logo

The Structures of Secretory and Dimeric Immunoglobulin A

By Sonya Kumar Bharathkar, Benjamin W. Parker, Andrey G. Malyutin, Nandan Haloi, Kathryn E. Huey-Tubman, Emad Tajkhorshid, Beth M. Stadtmueller

Posted 17 Feb 2020
bioRxiv DOI: 10.1101/2020.02.16.951780 (published DOI: 10.7554/eLife.56098)

Secretory (S) Immunoglobulin (I) A is the predominant mucosal antibody, which binds pathogens and commensal microbes. SIgA is a polymeric antibody, typically containing two copies of IgA that assemble with one joining-chain (JC) to form dimeric (d) IgA that is bound by the polymeric Ig-receptor ectodomain, called secretory component (SC). Here we report the cryo-electron microscopy structures of murine SIgA and dIgA. Structures reveal two IgAs conjoined through four heavy-chain tailpieces and the JC that together form a β-sandwich-like fold. The two IgAs are bent and tilted with respect to each other, forming distinct concave and convex surfaces. In SIgA, SC is bound to one face, asymmetrically contacting both IgAs and JC. The bent and tilted arrangement of complex components limits the possible positions of both sets of antigen binding fragments (Fabs) and preserves steric accessibility to receptor binding sites, likely influencing antigen binding and effector functions. ### Competing Interest Statement The authors have declared no competing interest.

Download data

  • Downloaded 880 times
  • Download rankings, all-time:
    • Site-wide: 25,457
    • In immunology: 748
  • Year to date:
    • Site-wide: 34,121
  • Since beginning of last month:
    • Site-wide: 66,546

Altmetric data


Downloads over time

Distribution of downloads per paper, site-wide


PanLingua

Sign up for the Rxivist weekly newsletter! (Click here for more details.)


News