View source for 5tcx


==Crystal structure of human tetraspanin CD81==
<StructureSection load='5tcx' size='340' side='right'caption='[[5tcx]], [[Resolution|resolution]] 2.96&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5tcx]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5TCX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5TCX 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]] 2.955&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CLR:CHOLESTEROL'>CLR</scene>, <scene name='pdbligand=YCM:S-(2-AMINO-2-OXOETHYL)-L-CYSTEINE'>YCM</scene></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=5tcx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5tcx OCA], [https://pdbe.org/5tcx PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5tcx RCSB], [https://www.ebi.ac.uk/pdbsum/5tcx PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5tcx ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/CD81_HUMAN CD81_HUMAN] Defects in CD81 are the cause of immunodeficiency common variable type 6 (CVID6) [MIM:[https://omim.org/entry/613496 613496]; also called antibody deficiency due to CD81 defect. CVID6 is a primary immunodeficiency characterized by antibody deficiency, hypogammaglobulinemia, recurrent bacterial infections and an inability to mount an antibody response to antigen. The defect results from a failure of B-cell differentiation and impaired secretion of immunoglobulins; the numbers of circulating B-cells is usually in the normal range, but can be low.<ref>PMID:20237408</ref> 
== Function ==
[https://www.uniprot.org/uniprot/CD81_HUMAN CD81_HUMAN] May play an important role in the regulation of lymphoma cell growth. Interacts with a 16-kDa Leu-13 protein to form a complex possibly involved in signal transduction. May act as the viral receptor for HCV.
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== Publication Abstract from PubMed ==
Tetraspanins comprise a diverse family of four-pass transmembrane proteins that play critical roles in the immune, reproductive, genitourinary, and auditory systems. Despite their pervasive roles in human physiology, little is known about the structure of tetraspanins or the molecular mechanisms underlying their various functions. Here, we report the crystal structure of human CD81, a full-length tetraspanin. The transmembrane segments of CD81 pack as two largely separated pairs of helices, capped by the large extracellular loop (EC2) at the outer membrane leaflet. The two pairs of helices converge at the inner leaflet to create an intramembrane pocket with additional electron density corresponding to a bound cholesterol molecule within the cavity. Molecular dynamics simulations identify an additional conformation in which EC2 separates substantially from the transmembrane domain. Cholesterol binding appears to modulate CD81 activity in cells, suggesting a potential mechanism for regulation of tetraspanin function.

Crystal Structure of a Full-Length Human Tetraspanin Reveals a Cholesterol-Binding Pocket.,Zimmerman B, Kelly B, McMillan BJ, Seegar TC, Dror RO, Kruse AC, Blacklow SC Cell. 2016 Nov 3;167(4):1041-1051.e11. doi: 10.1016/j.cell.2016.09.056. Epub 2016, Oct 27. PMID:27881302<ref>PMID:27881302</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 5tcx" style="background-color:#fffaf0;"></div>

==See Also==
*[[CD81|CD81]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Blacklow SC]]
[[Category: Kruse AC]]
[[Category: McMillan BJ]]
[[Category: Seegar TCM]]
[[Category: Zimmerman B]]