View source for 1kg0


==Structure of the Epstein-Barr Virus gp42 Protein Bound to the MHC class II Receptor HLA-DR1==
<StructureSection load='1kg0' size='340' side='right'caption='[[1kg0]], [[Resolution|resolution]] 2.65&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1kg0]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Ebvg Ebvg] and [http://en.wikipedia.org/wiki/Human Human]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KG0 OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=1KG0 FirstGlance]. <br>
</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=1kg0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1kg0 OCA], [http://pdbe.org/1kg0 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1kg0 RCSB], [http://www.ebi.ac.uk/pdbsum/1kg0 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1kg0 ProSAT]</span></td></tr>
</table>
== Disease ==
[[http://www.uniprot.org/uniprot/2B11_HUMAN 2B11_HUMAN]] Genetic variation in HLA-DRB1 is a cause of susceptibility to sarcoidosis type 1 (SS1) [MIM:[http://omim.org/entry/181000 181000]]. Sarcoidosis is an idiopathic, systemic, inflammatory disease characterized by the formation of immune granulomas in involved organs. Granulomas predominantly invade the lungs and the lymphatic system, but also skin, liver, spleen, eyes and other organs may be involved.<ref>PMID:14508706</ref>  
== Function ==
[[http://www.uniprot.org/uniprot/GP42_EBVB9 GP42_EBVB9]] Plays a role in virion attachment to host B-lymphocytes, through binding to leukocyte antigen (HLA) class II and subsequently participates in fusion of the virion with host membranes. May act as a tropism switch that directs fusion with B-lymphocytes and inhibits fusion with epithelial cells.<ref>PMID:12042810</ref>  [[http://www.uniprot.org/uniprot/DRA_HUMAN DRA_HUMAN]] Binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for recognition by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mostly by degradation of proteins that access the endocytic route, where they are processed by lysosomal proteases and other hydrolases. Exogenous antigens that have been endocytosed by the APC are thus readily available for presentation via MHC II molecules, and for this reason this antigen presentation pathway is usually referred to as exogenous. As membrane proteins on their way to degradation in lysosomes as part of their normal turn-over are also contained in the endosomal/lysosomal compartments, exogenous antigens must compete with those derived from endogenous components. Autophagy is also a source of endogenous peptides, autophagosomes constitutively fuse with MHC class II loading compartments. In addition to APCs, other cells of the gastrointestinal tract, such as epithelial cells, express MHC class II molecules and CD74 and act as APCs, which is an unusual trait of the GI tract. To produce a MHC class II molecule that presents an antigen, three MHC class II molecules (heterodimers of an alpha and a beta chain) associate with a CD74 trimer in the ER to form a heterononamer. Soon after the entry of this complex into the endosomal/lysosomal system where antigen processing occurs, CD74 undergoes a sequential degradation by various proteases, including CTSS and CTSL, leaving a small fragment termed CLIP (class-II-associated invariant chain peptide). The removal of CLIP is facilitated by HLA-DM via direct binding to the alpha-beta-CLIP complex so that CLIP is released. HLA-DM stabilizes MHC class II molecules until primary high affinity antigenic peptides are bound. The MHC II molecule bound to a peptide is then transported to the cell membrane surface. In B-cells, the interaction between HLA-DM and MHC class II molecules is regulated by HLA-DO. Primary dendritic cells (DCs) also to express HLA-DO. Lysosomal miroenvironment has been implicated in the regulation of antigen loading into MHC II molecules, increased acidification produces increased proteolysis and efficient peptide loading. [[http://www.uniprot.org/uniprot/2B11_HUMAN 2B11_HUMAN]] Binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for recognition by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mostly by degradation of proteins that access the endocytic route; where they are processed by lysosomal proteases and other hydrolases. Exogenous antigens that have been endocytosed by the APC are thus readily available for presentation via MHC II molecules; and for this reason this antigen presentation pathway is usually referred to as exogenous. As membrane proteins on their way to degradation in lysosomes as part of their normal turn-over are also contained in the endosomal/lysosomal compartments; exogenous antigens must compete with those derived from endogenous components. Autophagy is also a source of endogenous peptides; autophagosomes constitutively fuse with MHC class II loading compartments. In addition to APCs; other cells of the gastrointestinal tract; such as epithelial cells; express MHC class II molecules and CD74 and act as APCs; which is an unusual trait of the GI tract. To produce a MHC class II molecule that presents an antigen; three MHC class II molecules (heterodimers of an alpha and a beta chain) associate with a CD74 trimer in the ER to form a heterononamer. Soon after the entry of this complex into the endosomal/lysosomal system where antigen processing occurs; CD74 undergoes a sequential degradation by various proteases; including CTSS and CTSL; leaving a small fragment termed CLIP (class-II-associated invariant chain peptide). The removal of CLIP is facilitated by HLA-DM via direct binding to the alpha-beta-CLIP complex so that CLIP is released. HLA-DM stabilizes MHC class II molecules until primary high affinity antigenic peptides are bound. The MHC II molecule bound to a peptide is then transported to the cell membrane surface. In B-cells; the interaction between HLA-DM and MHC class II molecules is regulated by HLA-DO. Primary dendritic cells (DCs) also to express HLA-DO. Lysosomal miroenvironment has been implicated in the regulation of antigen loading into MHC II molecules; increased acidification produces increased proteolysis and efficient peptide loading. 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/kg/1kg0_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1kg0 ConSurf].
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== Publication Abstract from PubMed ==
Epstein-Barr virus (EBV) causes infectious mononucleosis, establishes long-term latent infections, and is associated with a variety of human tumors. The EBV gp42 glycoprotein binds MHC class II molecules, playing a critical role in infection of B lymphocytes. EBV gp42 belongs to the C-type lectin superfamily, with homology to NK receptors of the immune system. We report the crystal structure of gp42 bound to the human MHC class II molecule HLA-DR1. The gp42 binds HLA-DR1 using a surface site that is distinct from the canonical lectin and NK receptor ligand binding sites. At the canonical ligand binding site, gp42 forms a large hydrophobic groove, which could interact with other ligands necessary for EBV entry, providing a mechanism for coupling MHC recognition and membrane fusion.

Structure of the Epstein-Barr virus gp42 protein bound to the MHC class II receptor HLA-DR1.,Mullen MM, Haan KM, Longnecker R, Jardetzky TS Mol Cell. 2002 Feb;9(2):375-85. PMID:11864610<ref>PMID:11864610</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Ebvg]]
[[Category: Human]]
[[Category: Large Structures]]
[[Category: Haan, K M]]
[[Category: Jardetzky, T S]]
[[Category: Longnecker, R]]
[[Category: Mullen, M M]]
[[Category: C-type lectin domain]]
[[Category: Membrane fusion]]
[[Category: Mhc]]
[[Category: Viral protein-immune system complex]]
[[Category: Virus]]