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.
Crystal structure of the extracellular segment of integrin alpha Vbeta3.,Xiong JP, Stehle T, Diefenbach B, Zhang R, Dunker R, Scott DL, Joachimiak A, Goodman SL, Arnaout MA Science. 2001 Oct 12;294(5541):339-45. Epub 2001 Sep 6. PMID:11546839
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