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| [[Image:2oz4.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2oz4| PDB=2oz4 | SCENE= }} | | {{STRUCTURE_2oz4| PDB=2oz4 | SCENE= }} |
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| '''Structural Plasticity in IgSF Domain 4 of ICAM-1 Mediates Cell Surface Dimerization'''
| | ===Structural Plasticity in IgSF Domain 4 of ICAM-1 Mediates Cell Surface Dimerization=== |
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| ==Overview==
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| The Ig superfamily (IgSF) intercellular adhesion molecule-1 (ICAM-1) equilibrates between monomeric and dimeric forms on the cell surface, and dimerization enhances cell adhesion. A crystal structure of ICAM-1 IgSF domains (D) 3-5 revealed a unique dimerization interface in which D4s of two protomers fuse through edge beta-strands to form a single super beta-sandwich domain. Here, we describe a crystal structure at 2.7-A resolution of monomeric ICAM-1 D3-D5, stabilized by the monomer-specific Fab CA7. CA7 binds to D5 in a region that is buried in the dimeric interface and is distal from the dimerization site in D4. In monomeric ICAM-1 D3-D5, a 16-residue loop in D4 that is disordered in the dimeric structure could clearly be traced as a BC loop, a short C strand, and a CE meander with a cis-Pro followed by a solvent-exposed, flexible four-residue region. Deletions of 6 or 10 residues showed that the C-strand is essential for monomer stability, whereas a distinct six-residue deletion showed little contribution of the CE meander. Mutation of two inward-pointing Leu residues in edge beta-strand E to Lys increased monomer stability, confirming the hypothesis that inward-pointing charged side chains on edge beta-strands are an important design feature to prevent beta-supersheet formation. Overall, the studies reveal that monomer-dimer transition is associated with a surprisingly large, physiologically relevant, IgSF domain rearrangement. | | The line below this paragraph, {{ABSTRACT_PUBMED_17881562}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17881562 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17881562}} |
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| ==Disease== | | ==Disease== |
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| [[Category: Igsf domain]] | | [[Category: Igsf domain]] |
| [[Category: Structural plasticity]] | | [[Category: Structural plasticity]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 11:58:15 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 15:36:24 2008'' |
