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From Proteopedia
Solution structure of human secretory component
Structural highlights
FunctionPIGR_HUMAN This receptor 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. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSecretory component (SC) in association with polymeric IgA (pIgA) forms secretory IgA, the major antibody active at mucosal surfaces. SC also exists in the free form, with innate-like neutralizing properties against pathogens. Free SC consists of five glycosylated variable (V)-type Ig domains (D1-D5), whose structure was determined by x-ray and neutron scattering, ultracentrifugation, and modeling. With a radius of gyration of 3.53-3.63 nm, a length of 12.5 nm, and a sedimentation coefficient of 4.0 S, SC possesses an unexpected compact structure. Constrained scattering modeling based on up to 13,000 trial models shows that SC adopts a J-shaped structure in which D4 and D5 are folded back against D2 and D3. The seven glycosylation sites are located on one side of SC, leaving known IgA-binding motifs free to interact with pIgA. This work represents the first analysis of the three-dimensional structure of full-length free SC and paves the way to a better understanding of the association between SC and its potential ligands, i.e. pIgA and pathogenic-associated motifs. Solution structure of human secretory component and implications for biological function.,Bonner A, Perrier C, Corthesy B, Perkins SJ J Biol Chem. 2007 Jun 8;282(23):16969-80. Epub 2007 Apr 11. PMID:17428798[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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