title: Crystal structure of the extracellular segment of integrin alpha Vbeta3.
abstract: Integrins are alphabeta heterodimeric receptors that mediate divalent cation-dependent cell-cell and cell-matrix adhesion through tightly regulated interactions with ligands. We have solved the crystal structure of the extracellular portion of integrin alphaVbeta3 at 3.1 A resolution. Its 12 domains assemble into an ovoid "head" and two "tails." In the crystal, alphaVbeta3 is severely bent at a defined region in its tails, reflecting an unusual flexibility that may be linked to integrin regulation. The main inter-subunit interface lies within the head, between a seven-bladed beta-propeller from alphaV and an A domain from beta3, and bears a striking resemblance to the Galpha/Gbeta interface in G proteins. A metal ion-dependent adhesion site (MIDAS) in the betaA domain is positioned to participate in a ligand-binding interface formed of loops from the propeller and betaA domains. MIDAS lies adjacent to a calcium-binding site with a potential regulatory function.
authors.affiliation: Renal Unit, Leukocyte Biology & Inflammation Program, Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, MA 02129, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Xiong
authors.forename: T
authors.initials: T
authors.lastname: Stehle
authors.forename: B
authors.initials: B
authors.lastname: Diefenbach
authors.forename: R
authors.initials: R
authors.lastname: Zhang
authors.forename: R
authors.initials: R
authors.lastname: Dunker
authors.forename: D L
authors.initials: DL
authors.lastname: Scott
authors.forename: A
authors.initials: A
authors.lastname: Joachimiak
authors.forename: S L
authors.initials: SL
authors.lastname: Goodman
authors.forename: M A
authors.initials: MA
authors.lastname: Arnaout
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D006801:Humans; D008024:Ligands; D008670:Metals / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D019030:Receptors, Vitronectin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D008024:Ligands; D008670:Metals; D021122:Protein Subunits; D019030:Receptors, Vitronectin; D002118:Calcium