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Crystal structure of human Ig-beta homodimerCrystal structure of human Ig-beta homodimer
Structural highlights
DiseaseCD79B_HUMAN Autosomal agammaglobulinemia. Defects in CD79B are the cause of agammaglobulinemia type 6 (AGM6) [MIM:612692. It is a primary immunodeficiency characterized by profoundly low or absent serum antibodies and low or absent circulating B-cells due to an early block of B-cell development. Affected individuals develop severe infections in the first years of life.[1] FunctionCD79B_HUMAN Required in cooperation with CD79A for initiation of the signal transduction cascade activated by the B-cell antigen receptor complex (BCR) which leads to internalization of the complex, trafficking to late endosomes and antigen presentation. Enhances phosphorylation of CD79A, possibly by recruiting kinases which phosphorylate CD79A or by recruiting proteins which bind to CD79A and protect it from dephosphorylation.[2] [3] [4] 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 PubMedThe B cell antigen receptor (BCR) plays an essential role in all phases of B cell development. Here we show that the extracellular domains of murine and human Igbeta form an I-set immunoglobulin-like structure with an interchain disulfide between cysteines on their G strands. Structural and sequence analysis suggests that Igalpha displays a similar fold as Igbeta. An Igalphabeta heterodimer model was generated based on the unique disulfide-bonded Igbeta dimer. Solution binding studies showed that the extracellular domains of Igalphabeta preferentially recognize the constant region of BCR with mu chain specificity, suggesting a role for Igalphabeta to enhance BCRmu chain signaling. Cluster mutations on Igalpha, Igbeta, and a membrane-bound form of immunoglobulin (mIgM) based on the structural model identified distinct areas of potential contacts involving charged residues on both subunits of the coreceptor and the Cmu4 domain of mIgM. These studies provide the first structural model for understanding BCR function. Structural and functional studies of Igalphabeta and its assembly with the B cell antigen receptor.,Radaev S, Zou Z, Tolar P, Nguyen K, Nguyen A, Krueger PD, Stutzman N, Pierce S, Sun PD Structure. 2010 Aug 11;18(8):934-43. PMID:20696394[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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