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From Proteopedia
Crystal structure of human FcaRI bound to IgA1-Fc
Structural highlights
DiseaseIGHA1_HUMAN Note=A chromosomal aberration involving IGHA1 is found in multiple myeloma (MM) cell lines. Translocation t(1;14)(q21;q32) that forms a FCRL4-IGHA1 fusion protein. FunctionIGHA1_HUMAN Ig alpha is the major immunoglobulin class in body secretions. It may serve both to defend against local infection and to prevent access of foreign antigens to the general immunologic system. 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 PubMedImmunoglobulin-alpha (IgA)-bound antigens induce immune effector responses by activating the IgA-specific receptor FcalphaRI (CD89) on immune cells. Here we present crystal structures of human FcalphaRI alone and in a complex with the Fc region of IgA1 (Fcalpha). FcalphaRI has two immunoglobulin-like domains that are oriented at approximately right angles to each other. Fcalpha resembles the Fcs of immunoglobulins IgG and IgE, but has differently located interchain disulphide bonds and external rather than interdomain N-linked carbohydrates. Unlike 1:1 FcgammaRIII:IgG and Fc epsilon RI:IgE complexes, two FcalphaRI molecules bind each Fcalpha dimer, one at each Calpha2-Calpha3 junction. The FcalphaRI-binding site on IgA1 overlaps the reported polymeric immunoglobulin receptor (pIgR)-binding site, which might explain why secretory IgA cannot initiate phagocytosis or bind to FcalphaRI-expressing cells in the absence of an integrin co-receptor. Insights into IgA-mediated immune responses from the crystal structures of human FcalphaRI and its complex with IgA1-Fc.,Herr AB, Ballister ER, Bjorkman PJ Nature. 2003 Jun 5;423(6940):614-20. Epub 2003 May 21. PMID:12768205[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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