Secretory IgA (S-IgA) has been shown to possess unique immunochemical and physicochemical properties due to its polymeric nature, which binds to an epithelial glycoprotein called secretory piece (SP) or secretory component (SC) for transport to body fluids in vitro. As a leading biotechnology company, Creative Biolabs provides IgA receptor-related resource presentations in addition to non-IgG antibody products and services to support the specific needs of customers worldwide.
Introduction of SC receptor
SC receptor is a type of classical IgA receptor that is present on the surface of certain glandular epithelial and hepatic cells, including epithelial and endothelial cells. It is responsible for binding and transporting secretory IgA (sIgA) antibodies across mucosal surfaces, such as in the respiratory, gastrointestinal, and urogenital tracts. Once the SC receptor binds to sIgA, it is transported across the mucosal surface to help prevent infection by neutralizing pathogens and toxins. SC receptors are important components of the mucosal immune system and are being investigated as potential targets for immunotherapy against infectious diseases.
The human SC gene is located on the long arm of chromosome 1 (region q31-q42). This region contains other immunologically significant genes and is involved in a large number of recombination events. Human SC appears in three molecular forms. The first is a basolateral transmembrane protein that functions as the pIg receptor (pIgR); the second is a stable component of S-IgA and S-IgM; and the third is that excess free SC is present in most exocrine fluids. The SC transmembrane structure contains five homologous extracellular structural domains, a transmembrane anchor, and a cytoplasmic tail. Hydrolytic cleavage of proteins near the apical cell membrane releases SC (in the bound or free state) into the exocytosis. These additional functions suggest a phylogenetic origin of SC in the innate defense system.
Schematic depiction of the mature human transmembrane SC
Function of SC receptor
As a specific receptor of IgA, SC receptor plays an important role in the synthesis, secretion and transport of SIgA, and can protect SIgA from degradation by proteolytic enzymes. Under normal conditions, IgA immunoglobulin enters the intestine through the lymphatic vessels and then enters the intestinal lumen through the enterocytes. During this period, IgA binds to SC to form the IgA-SC complex. The SC-pIgA system is a unique form of receptor-ligand reaction. After binding to the ligand, the receptor is neither recycled nor degraded, but is secreted by cells after forming complexes with the ligand and promotes IgA secretion on the mucosal surface of the intestine. IgA-SC complexes also contribute to binding to gut bacteria and other microorganisms, thereby enhancing the function of the intestinal immune system.
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- Brandtzaeg, P.; et al. Secretory Component (The Polymeric Ig Receptor). Encyclopedia of Immunology, 1998, 2152–2158.
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