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[[Image:1b0g.jpg|left|200px]]<br /><applet load="1b0g" size="350" color="white" frame="true" align="right" spinBox="true"
caption="1b0g, resolution 2.5&Aring;" />
'''CLASS I HISTOCOMPATIBILITY ANTIGEN (HLA-A2.1)/BETA 2-MICROGLOBULIN/PEPTIDE P1049 COMPLEX'''<br />


==Overview==
==CLASS I HISTOCOMPATIBILITY ANTIGEN (HLA-A2.1)/BETA 2-MICROGLOBULIN/PEPTIDE P1049 COMPLEX==
The T cell receptor (TCR), from a xeno-reactive murine cytotoxic T, lymphocyte clone AHIII12.2, recognizes murine H-2Db complexed with peptide, p1027 (FAPGVFPYM), as well as human HLA-A2.1 complexed with peptide p1049, (ALWGFFPVL). A commonly proposed model (the molecular mimicry model) used, to explain TCR cross-reactivity suggests that the molecular surfaces of, the recognized complexes are similar in shape, charge, or both, in spite, of the primary sequence differences. To examine the mechanism of, xeno-reactivity of AHIII12.2, we have determined the crystal structures of, A2/p1049 and Db/p1027 to 2.5 A and 2.8 A resolution, respectively. The, crystal structures show that the TCR footprint regions of the two class I, complexes are significantly different in shape and charge. We propose that, rather than simple molecular mimicry, unpredictable arrays of common and, differential contacts on the two class I complexes are used for their, recognition by the same TCR.
<StructureSection load='1b0g' size='340' side='right'caption='[[1b0g]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1b0g]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=1a9k 1a9k]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1B0G OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1B0G FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1b0g FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1b0g OCA], [https://pdbe.org/1b0g PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1b0g RCSB], [https://www.ebi.ac.uk/pdbsum/1b0g PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1b0g ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/B2MG_HUMAN B2MG_HUMAN] Defects in B2M are the cause of hypercatabolic hypoproteinemia (HYCATHYP) [MIM:[https://omim.org/entry/241600 241600]. Affected individuals show marked reduction in serum concentrations of immunoglobulin and albumin, probably due to rapid degradation.<ref>PMID:16549777</ref>  Note=Beta-2-microglobulin may adopt the fibrillar configuration of amyloid in certain pathologic states. The capacity to assemble into amyloid fibrils is concentration dependent. Persistently high beta(2)-microglobulin serum levels lead to amyloidosis in patients on long-term hemodialysis.<ref>PMID:3532124</ref> <ref>PMID:1336137</ref> <ref>PMID:7554280</ref> <ref>PMID:4586824</ref> <ref>PMID:8084451</ref> <ref>PMID:12119416</ref> <ref>PMID:12796775</ref> <ref>PMID:16901902</ref> <ref>PMID:16491088</ref> <ref>PMID:17646174</ref> <ref>PMID:18835253</ref> <ref>PMID:18395224</ref> <ref>PMID:19284997</ref>
== Function ==
[https://www.uniprot.org/uniprot/B2MG_HUMAN B2MG_HUMAN] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.
== 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/b0/1b0g_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=1b0g ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The T cell receptor (TCR), from a xeno-reactive murine cytotoxic T lymphocyte clone AHIII12.2, recognizes murine H-2Db complexed with peptide p1027 (FAPGVFPYM), as well as human HLA-A2.1 complexed with peptide p1049 (ALWGFFPVL). A commonly proposed model (the molecular mimicry model) used to explain TCR cross-reactivity suggests that the molecular surfaces of the recognized complexes are similar in shape, charge, or both, in spite of the primary sequence differences. To examine the mechanism of xeno-reactivity of AHIII12.2, we have determined the crystal structures of A2/p1049 and Db/p1027 to 2.5 A and 2.8 A resolution, respectively. The crystal structures show that the TCR footprint regions of the two class I complexes are significantly different in shape and charge. We propose that rather than simple molecular mimicry, unpredictable arrays of common and differential contacts on the two class I complexes are used for their recognition by the same TCR.


==Disease==
Structural evidence of T cell xeno-reactivity in the absence of molecular mimicry.,Zhao R, Loftus DJ, Appella E, Collins EJ J Exp Med. 1999 Jan 18;189(2):359-70. PMID:9892618<ref>PMID:9892618</ref>
Known diseases associated with this structure: Abacavir hypersensitivity, susceptibility to OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=142800 142800]], Ankylosing spondylitis, susceptibility to, 1 OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=142800 142800]], Hypoproteinemia, hypercatabolic OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=109700 109700]], Stevens-Johnson syndrome, susceptibility to OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=142800 142800]]


==About this Structure==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
1B0G is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. This structure superseeds the now removed PDB entry 1A9K. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1B0G OCA].
</div>
<div class="pdbe-citations 1b0g" style="background-color:#fffaf0;"></div>


==Reference==
==See Also==
Structural evidence of T cell xeno-reactivity in the absence of molecular mimicry., Zhao R, Loftus DJ, Appella E, Collins EJ, J Exp Med. 1999 Jan 18;189(2):359-70. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=9892618 9892618]
*[[Beta-2 microglobulin 3D structures|Beta-2 microglobulin 3D structures]]
*[[MHC 3D structures|MHC 3D structures]]
*[[MHC I 3D structures|MHC I 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
[[Category: Protein complex]]
[[Category: Large Structures]]
[[Category: Collins, E.J.]]
[[Category: Collins EJ]]
[[Category: Zhao, R.]]
[[Category: Zhao R]]
[[Category: class i histocompatibility antigen (hla-a2.1)/beta 2-microglobulin/peptide p1049 complex]]
 
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