Molecular characteristics of IgA and IgM Fc binding to the Fcalpha/muR.
Fcalpha/mu receptor (Fcalpha/muR), a novel Fc receptor for IgA and IgM, is a type I transmembrane protein with an immunoglobulin (Ig)-like domain in the extracellular portion. Although IgA and IgM bind to Fcalpha/muR, the molecular and structural characteristics of the ligand-receptor interactions have been undetermined. Here, we developed twelve monoclonal antibodies (mAbs) against murine Fcalpha/muR by immunizing mice deficient in Fcalpha/muR gene. Eight mAbs totally or partially blocked IgA and IgM bindings to Fcalpha/muR. These blocking mAbs bound to a peptide derived from the Ig-like domain of murine Fcalpha/muR, which is conserved not only in human and rat Fcalpha/muR but also in polymeric Ig receptor (poly-IgR), another Fc receptor for IgA and IgM. These results suggest that IgA and IgM bind to an epitope in the conserved amino acids in the Ig-like domain of Fcalpha/muR as well as poly-IgR.
Cho
Yukiko
Y
Department of Immunology, Institute of Basic Medical Sciences, Graduate School of Comprehensive Human Sciences and Center for TARA, University of Tsukuba, 1-1-1 Tennodai, Tsukuba Science City, Ibaraki 305-8575, Japan.
Usui
Kenta
K
Honda
Shin-Ichiro
S
Tahara-Hanaoka
Satoko
S
Shibuya
Kazuko
K
Shibuya
Akira
A