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==Re-refinement of the Crystal Structure of the Plexin-Semaphorin-Integrin Domain/Hybrid Domain/I-EGF1 Segment from the Human Integrin b2 Subunit==
==Re-refinement of the Crystal Structure of the Plexin-Semaphorin-Integrin Domain/Hybrid Domain/I-EGF1 Segment from the Human Integrin b2 Subunit==
<StructureSection load='5e6x' size='340' side='right' caption='[[5e6x]], [[Resolution|resolution]] 1.75&Aring;' scene=''>
<StructureSection load='5e6x' size='340' side='right'caption='[[5e6x]], [[Resolution|resolution]] 1.75&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[5e6x]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5E6X OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5E6X FirstGlance]. <br>
<table><tr><td colspan='2'>[[5e6x]] 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=5E6X OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5E6X FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene></td></tr>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.75&#8491;</td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[2p26|2p26]]</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene></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=5e6x FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5e6x OCA], [http://pdbe.org/5e6x PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5e6x RCSB], [http://www.ebi.ac.uk/pdbsum/5e6x PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5e6x ProSAT]</span></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=5e6x FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5e6x OCA], [https://pdbe.org/5e6x PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5e6x RCSB], [https://www.ebi.ac.uk/pdbsum/5e6x PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5e6x ProSAT]</span></td></tr>
</table>
</table>
== Disease ==
== Disease ==
[[http://www.uniprot.org/uniprot/ITB2_HUMAN ITB2_HUMAN]] Defects in ITGB2 are the cause of leukocyte adhesion deficiency type 1 (LAD1) [MIM:[http://omim.org/entry/116920 116920]]. LAD1 patients have recurrent bacterial infections and their leukocytes are deficient in a wide range of adhesion-dependent functions.<ref>PMID:7509236</ref> <ref>PMID:1346613</ref> <ref>PMID:1968911</ref> <ref>PMID:1694220</ref> <ref>PMID:1590804</ref> <ref>PMID:1352501</ref> <ref>PMID:1347532</ref> <ref>PMID:7686755</ref> <ref>PMID:9884339</ref> <ref>PMID:20529581</ref> <ref>PMID:20549317</ref>
[https://www.uniprot.org/uniprot/ITB2_HUMAN ITB2_HUMAN] Defects in ITGB2 are the cause of leukocyte adhesion deficiency type 1 (LAD1) [MIM:[https://omim.org/entry/116920 116920]. LAD1 patients have recurrent bacterial infections and their leukocytes are deficient in a wide range of adhesion-dependent functions.<ref>PMID:7509236</ref> <ref>PMID:1346613</ref> <ref>PMID:1968911</ref> <ref>PMID:1694220</ref> <ref>PMID:1590804</ref> <ref>PMID:1352501</ref> <ref>PMID:1347532</ref> <ref>PMID:7686755</ref> <ref>PMID:9884339</ref> <ref>PMID:20529581</ref> <ref>PMID:20549317</ref>  
== Function ==
== Function ==
[[http://www.uniprot.org/uniprot/ITB2_HUMAN ITB2_HUMAN]] Integrin alpha-L/beta-2 is a receptor for ICAM1, ICAM2, ICAM3 and ICAM4. Integrins alpha-M/beta-2 and alpha-X/beta-2 are receptors for the iC3b fragment of the third complement component and for fibrinogen. Integrin alpha-X/beta-2 recognizes the sequence G-P-R in fibrinogen alpha-chain. Integrin alpha-M/beta-2 recognizes P1 and P2 peptides of fibrinogen gamma chain. Integrin alpha-M/beta-2 is also a receptor for factor X. Integrin alpha-D/beta-2 is a receptor for ICAM3 and VCAM1. Triggers neutrophil transmigration during lung injury through PTK2B/PYK2-mediated activation.<ref>PMID:18587400</ref>
[https://www.uniprot.org/uniprot/ITB2_HUMAN ITB2_HUMAN] Integrin alpha-L/beta-2 is a receptor for ICAM1, ICAM2, ICAM3 and ICAM4. Integrins alpha-M/beta-2 and alpha-X/beta-2 are receptors for the iC3b fragment of the third complement component and for fibrinogen. Integrin alpha-X/beta-2 recognizes the sequence G-P-R in fibrinogen alpha-chain. Integrin alpha-M/beta-2 recognizes P1 and P2 peptides of fibrinogen gamma chain. Integrin alpha-M/beta-2 is also a receptor for factor X. Integrin alpha-D/beta-2 is a receptor for ICAM3 and VCAM1. Triggers neutrophil transmigration during lung injury through PTK2B/PYK2-mediated activation.<ref>PMID:18587400</ref>  
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<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
Integrins mediate cell adhesion in response to activation signals that trigger conformational changes within their ectodomain. It is thought that a compact bent conformation of the molecule represents its physiological low affinity state and extended conformations its active state. We have determined the structure of two integrin fragments of the beta2 subunit. The first structure, consisting of the plexin-semaphorin-integrin domain, hybrid, integrin-epidermal growth factor 1 (I-EGF1), and I-EGF2 domains (PHE2), showed an L-shaped conformation with the bend located between the I-EGF1 and I-EGF2 domains. The second structure, which includes, in addition, the I-EGF3 domain, showed an extended conformation. The major reorientation of I-EGF2 with respect to the other domains in the two structures is accompanied by a change of torsion angle of the disulfide bond between Cys(461)-Cys(492) by 180 degrees and the conversion of a short alpha-helix (residues Ser(468)-Cys(475)) into a flexible coil. Based on the PHE2 structure, we introduced a disulfide bond between the plexin-semaphorin-integrin domain and I-EGF2 domains in the beta2 subunit. The resultant alphaLbeta2 integrin (leukocyte function-associated antigen-1) variant was locked in a bent state and could not be detected with the monoclonal antibody KIM127 in Mg(2+)/EGTA. However, it retained the binding activity to ICAM-1. These results provide a structural hypothesis for our understanding of the transition between the resting and active states of leukocyte function-associated antigen-1.
High-resolution crystal structures of the headpiece of lymphocyte function-associated antigen-1 (integrin alphaLbeta2) reveal how the alphaI domain interacts with its platform formed by the alpha-subunit beta-propeller and beta-subunit betaI domains. The alphaLbeta2 structures compared with alphaXbeta2 structures show that the alphaI domain, tethered through its N-linker and a disulfide to a stable beta-ribbon pillar near the center of the platform, can undergo remarkable pivoting and tilting motions that appear buffered by N-glycan decorations that differ between alphaL and alphaX subunits. Rerefined beta2 integrin structures reveal details including pyroglutamic acid at the beta2 N terminus and bending within the EGF1 domain. Allostery is relayed to the alphaI domain by an internal ligand that binds to a pocket at the interface between the beta-propeller and betaI domains. Marked differences between the alphaL and alphaX subunit beta-propeller domains concentrate near the binding pocket and alphaI domain interfaces. Remarkably, movement in allostery in the betaI domain of specificity determining loop 1 (SDL1) causes concerted movement of SDL2 and thereby tightens the binding pocket for the internal ligand.


A structural hypothesis for the transition between bent and extended conformations of the leukocyte beta2 integrins.,Shi M, Foo SY, Tan SM, Mitchell EP, Law SK, Lescar J J Biol Chem. 2007 Oct 12;282(41):30198-206. Epub 2007 Aug 1. PMID:17673459<ref>PMID:17673459</ref>
Leukocyte integrin alphaLbeta2 headpiece structures: The alphaI domain, the pocket for the internal ligand, and concerted movements of its loops.,Sen M, Springer TA Proc Natl Acad Sci U S A. 2016 Mar 15;113(11):2940-5. doi:, 10.1073/pnas.1601379113. Epub 2016 Mar 2. PMID:26936951<ref>PMID:26936951</ref>


From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
</div>
<div class="pdbe-citations 5e6x" style="background-color:#fffaf0;"></div>
<div class="pdbe-citations 5e6x" style="background-color:#fffaf0;"></div>
==See Also==
*[[Integrin 3D structures|Integrin 3D structures]]
== References ==
== References ==
<references/>
<references/>
__TOC__
__TOC__
</StructureSection>
</StructureSection>
[[Category: Sen, M]]
[[Category: Homo sapiens]]
[[Category: Springer, T A]]
[[Category: Large Structures]]
[[Category: Cd18 fragment]]
[[Category: Sen M]]
[[Category: Cell adhesion]]
[[Category: Springer TA]]

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