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| - | [[Image:1jlm.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1jlm| PDB=1jlm | SCENE= }} | | {{STRUCTURE_1jlm| PDB=1jlm | SCENE= }} |
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| - | '''I-DOMAIN FROM INTEGRIN CR3, MN2+ BOUND'''
| + | ===I-DOMAIN FROM INTEGRIN CR3, MN2+ BOUND=== |
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| - | ==Overview==
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| - | BACKGROUND: Integrins are plasma membrane proteins that mediate adhesion to other cells and to components of the extracellular matrix. Most integrins are constitutively inactive in resting cells, but are rapidly and reversibly activated in response to agonists, leading to highly regulated cell adhesion. This activation is associated with conformational changes in their extracellular portions, but the nature of the structural changes that lead to a change in adhesiveness is not understood. The interactions of several integrins with their extracellular ligands are mediated by an A-type domain (generally called the I-domain in integrins). Binding of the I-domain to protein ligands is dependent on divalent cations. We have described previously the structure of the I-domain from complement receptor 3 with bound Mg2+, in which the glutamate side chain from a second I-domain completes the octahedral coordination sphere of the metal, acting as a ligand mimetic. RESULTS: We now describe a new crystal form of the I-domain with bound Mn2+, in which water completes the metal coordination sphere and there is no equivalent of the glutamate ligand. Comparison of the two crystal forms reveals a change in metal coordination which is linked to a large (10 A) shift of the C-terminal helix and the burial of two phenylalanine residues into the hydrophobic core of the Mn2+ form. These structural changes, analogous to those seen in the signal-transducing G-proteins, alter the electrophilicity of the metal, reducing its ability to bind ligand-associated acidic residues, and dramatically alter the surface of the protein implicated in binding ligand. CONCLUSIONS: Our observations provide the first atomic resolution view of conformational changes in an integrin domain, and suggest how these changes are linked to a change in integrin adhesiveness. We propose that the Mg2+ form represents the conformation of the domain in the active state and the Mn2+ form the conformation in the inactive state of the integrin.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_8747460}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 8747460 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_8747460}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Glycoprotein]] | | [[Category: Glycoprotein]] |
| | [[Category: Integrin]] | | [[Category: Integrin]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 21:22:32 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 20:26:11 2008'' |
Revision as of 17:26, 1 July 2008
Template:STRUCTURE 1jlm
I-DOMAIN FROM INTEGRIN CR3, MN2+ BOUND
Template:ABSTRACT PUBMED 8747460
About this Structure
1JLM is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Two conformations of the integrin A-domain (I-domain): a pathway for activation?, Lee JO, Bankston LA, Arnaout MA, Liddington RC, Structure. 1995 Dec 15;3(12):1333-40. PMID:8747460
Page seeded by OCA on Tue Jul 1 20:26:11 2008
