6avr

<StructureSection load='6avr' size='340' side='right' caption='[[6avr]], [[Resolution|resolution]] 35.00&Aring;' scene=''>

<table><tr><td colspan='2'>[[6avr]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Human Human] and [http://en.wikipedia.org/wiki/Lk3_transgenic_mice Lk3 transgenic mice]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6AVR OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6AVR FirstGlance]. <br>

</td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[5opy|5opy]], [[6avq|6avq]]</td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">ITGAV, MSK8, VNRA, VTNR ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 HUMAN]), ITGB3, GP3A ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 HUMAN])</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6avr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6avr OCA], [http://pdbe.org/6avr PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6avr RCSB], [http://www.ebi.ac.uk/pdbsum/6avr PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6avr ProSAT]</span></td></tr>

== Disease ==

[[http://www.uniprot.org/uniprot/ITB3_HUMAN ITB3_HUMAN]] Defects in ITGB3 are a cause of Glanzmann thrombasthenia (GT) [MIM:[http://omim.org/entry/273800 273800]]; also known as thrombasthenia of Glanzmann and Naegeli. GT is the most common inherited disease of platelets. It is an autosomal recessive disorder characterized by mucocutaneous bleeding of mild-to-moderate severity and the inability of this integrin to recognize macromolecular or synthetic peptide ligands. GT has been classified clinically into types I and II. In type I, platelets show absence of the glycoprotein IIb/beta-3 complexes at their surface and lack fibrinogen and clot retraction capability. In type II, the platelets express the glycoprotein IIb/beta-3 complex at reduced levels (5-20% controls), have detectable amounts of fibrinogen, and have low or moderate clot retraction capability. The platelets of GT 'variants' have normal or near normal (60-100%) expression of dysfunctional receptors.<ref>PMID:2392682</ref> <ref>PMID:1371279</ref> <ref>PMID:1602006</ref> <ref>PMID:1438206</ref> <ref>PMID:8781422</ref> <ref>PMID:9376589</ref> <ref>PMID:9215749</ref> <ref>PMID:9790984</ref> <ref>PMID:9684783</ref> <ref>PMID:10233432</ref> <ref>PMID:11588040</ref> <ref>PMID:11897046</ref> <ref>PMID:12083483</ref> <ref>PMID:12353082</ref> <ref>PMID:15583747</ref> <ref>PMID:15634267</ref> <ref>PMID:15748237</ref>

[[http://www.uniprot.org/uniprot/ITAV_HUMAN ITAV_HUMAN]] The alpha-V integrins are receptors for vitronectin, cytotactin, fibronectin, fibrinogen, laminin, matrix metalloproteinase-2, osteopontin, osteomodulin, prothrombin, thrombospondin and vWF. They recognize the sequence R-G-D in a wide array of ligands. In case of HIV-1 infection, the interaction with extracellular viral Tat protein seems to enhance angiogenesis in Kaposi's sarcoma lesions. [[http://www.uniprot.org/uniprot/ITB3_HUMAN ITB3_HUMAN]] Integrin alpha-V/beta-3 is a receptor for cytotactin, fibronectin, laminin, matrix metalloproteinase-2, osteopontin, osteomodulin, prothrombin, thrombospondin, vitronectin and von Willebrand factor. Integrin alpha-IIb/beta-3 is a receptor for fibronectin, fibrinogen, plasminogen, prothrombin, thrombospondin and vitronectin. Integrins alpha-IIb/beta-3 and alpha-V/beta-3 recognize the sequence R-G-D in a wide array of ligands. Integrin alpha-IIb/beta-3 recognizes the sequence H-H-L-G-G-G-A-K-Q-A-G-D-V in fibrinogen gamma chain. Following activation integrin alpha-IIb/beta-3 brings about platelet/platelet interaction through binding of soluble fibrinogen. This step leads to rapid platelet aggregation which physically plugs ruptured endothelial surface. In case of HIV-1 infection, the interaction with extracellular viral Tat protein seems to enhance angiogenesis in Kaposi's sarcoma lesions.

The LM609 antibody specifically recognizes alphaVbeta3 integrin and inhibits angiogenesis, bone resorption, and viral infections in an arginine-glycine-aspartate-independent manner. LM609 entered phase II clinical trials for the treatment of several cancers and was also used for alphaVbeta3-targeted radioimmunotherapy. To elucidate the mechanisms of recognition and inhibition of alphaVbeta3 integrin, we solved the structure of the LM609 antigen-binding fragment by X-ray crystallography and determined its binding affinity for alphaVbeta3. Using single-particle electron microscopy, we show that LM609 binds at the interface between the beta-propeller domain of the alphaV chain and the betaI domain of the beta3 chain, near the RGD-binding site, of all observed integrin conformational states. Integrating these data with fluorescence size-exclusion chromatography, we demonstrate that LM609 sterically hinders access of large ligands to the RGD-binding pocket, without obstructing it. This work provides a structural framework to expedite future efforts utilizing LM609 as a diagnostic or therapeutic tool.

 

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== References ==

</StructureSection>

[[Category: Human]]

[[Category: Lk3 transgenic mice]]

[[Category: Backovic, M]]

[[Category: Borst, A J]]

[[Category: DiMaio, F]]

[[Category: Ginsberg, M]]

[[Category: James, Z N]]

[[Category: Rey, F A]]

[[Category: Veesler, D]]

[[Category: Zagotta, W N]]

[[Category: Vitaxin]]