Pigr
Domain
The Ig-like V-type 1/D1 domain contains three complementarity determining region-like loops CDR1-3, which mediate interaction with IgA and IgM.
Function
Polymeric immunoglobulin receptor
Mediates selective transcytosis of polymeric IgA and IgM across mucosal epithelial cells. Binds polymeric IgA and IgM at the basolateral surface of epithelial cells. The complex is then transported across the cell to be secreted at the apical surface. During this process, a cleavage occurs that separates the extracellular (known as the secretory component) from the transmembrane segment.
Secretory component
Through its N-linked glycans ensures anchoring of secretory IgA (sIgA) molecules to mucus lining the epithelial surface to neutralize extracellular pathogens. On its own (free form) may act as a non-specific microbial scavenger to prevent pathogen interaction with epithelial cells.
Post-translational modifications
N-glycosylated. N-glycosylation is required for anchoring IgA molecules to mucus, but is not necessary for Ig binding.
Cellular localization
- Polymeric immunoglobulin receptor
- Cell membrane
- Single-pass type I membrane protein
- Secretory component
- Secreted
Alternative names
Polymeric immunoglobulin receptor, PIgR, Poly-Ig receptor, Pigr