Invitrogen™ PIGR Monoclonal Antibody (7C1)

Polymeric IgA and IgM is produced and secreted by B cells in the lamina propria, which is beneath the mucosal lining of polarized epithelial cells. Polymeric immunoglobulin receptors, also designated pIgRs, are expressed on the basolateral surface of glandular epithelia and mediate transcellular transport of secretory immunoglobulin polymers across the epithelium. pIgR associates with secreted dimeric IgA and IgM molecules. During transcellular transport of these Ig polymers, pIgR undergoes proteolytic cleavage to generate a fragment called secretory component (SC), polymeric immunoglobulin receptor or poly-IG receptor. When immunoglobulin polymers associate with SC, they become resistant to enzymatic degradation during the transcytosis process. SC and the pIgR are crucial for proper mucosal immunity where they represent a molecular chaperone for polymeric Igs to remain intact and enter into body fluids. The human SC (pIgR) gene maps to chromosome 1q31-q41 and encodes a 764 amino acid protein. The receptor contains five units with homology to the variable (V) units of immunoglobulins and a transmembrane region that shares homology to certain immunoglobulin variable regions.