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.
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 .
Subcellular locations: Cell membrane
Subcellular locations: Secreted