secretory component

Proteolysis of the receptor occurs and the dimeric IgA molecule, along with the secretory component, are free to diffuse throughout the lumen.

The secretory component is a component of immunoglobulin A (IgA) which consists of a portion of the polymeric immunoglobulin receptor.

Some secretory components from the uterine glands are taken up by the secondary yolk sac lining the exocoelomic cavity during pregnancy, and may thereby assist in providing fetal nutrition.

The oligomeric forms of IgA in the external (mucosal) secretions also contain a polypeptide of a much larger molecular mass (70 kD) called the secretory component that is produced by epithelial cells.

The secretory component of sIgA protects the immunoglobulin from being degraded by proteolytic enzymes, thus sIgA can survive in the harsh gastrointestinal tract environment and provide protection against microbes that multiply in body secretions.