3lqa
From Proteopedia
Crystal structure of clade C gp120 in complex with sCD4 and 21c Fab
Structural highlights
Function[CD4_HUMAN] Accessory protein for MHC class-II antigen/T-cell receptor interaction. May regulate T-cell activation. Induces the aggregation of lipid rafts. [Q1PHM6_9HIV1] The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity).[SAAS:SAAS000328_004_020447][RuleBase:RU004292] The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity). 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 PubMedStrategies to combat HIV-1 require structural knowledge of envelope proteins from viruses in HIV-1 clade C, the most rapidly spreading subtype in the world. We present a crystal structure containing a clade C gp120 envelope. The structure, a complex between gp120, the host receptor CD4 and the CD4-induced antibody 21c, reveals that the 21c epitope involves contacts with gp120, a nonself antigen, and with CD4, an autoantigen. Binding studies using wild-type and mutant CD4 show that 21c Fab binds CD4 in the absence of gp120, and that binding of 21c to clade C and HIV-2 gp120s requires the crystallographically observed 21c-CD4 interaction. Additional binding data suggest a role for the gp120 V1V2 loop in creating a high-affinity, but slow-forming, epitope for 21c after CD4 binds. These results contribute to a molecular understanding of CD4-induced antibodies and provide the first visualization to our knowledge of a potentially autoreactive antibody Fab complexed with both self and nonself antigens. Structure of a clade C HIV-1 gp120 bound to CD4 and CD4-induced antibody reveals anti-CD4 polyreactivity.,Diskin R, Marcovecchio PM, Bjorkman PJ Nat Struct Mol Biol. 2010 May;17(5):608-13. Epub 2010 Mar 31. PMID:20357769[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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