Structural and evolutionary insights into FcαμR recognition of polymeric immunoglobulins

Authors

Zhang, M., Zhang, R., Wang, Y., Xiao, J.

Abstract

Polymeric immunoglobulins (pIgs) are central to adaptive immunity in jawed vertebrates. FcR is a bispecific pIg receptor that recognizes both IgM and IgA, but the molecular basis has been unclear. Here we determine cryo-EM structures of mammalian FcR bound to IgM or IgA and show that FcR engages each ligand in a 1:1 stoichiometry, with higher affinity for IgM. The FcR-binding site overlaps with those of pIgR, and also with the preferred FcR-binding site on IgM, yet distinct features distinguish FcR from both pIgR and FcR. Functionally, FcR efficiently internalizes both IgM and IgA through a pathway independent of the di-leucine motif. Structures of amphibian pIgR and FcR bound to IgM further shed light on the evolutionary diversification of the FcR/pIgR family. Together, these findings define the structural basis of FcR-mediated pIg recognition and provide a framework for understanding the evolution of pIg receptors.

Preprint server: bioRxiv
The authors list and abstract were imported from bioRxiv on 05 Nov 2026.

Stats

1-terrible, 9-excellent. How would you rate this preprint? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.