Ligand recognition by the I domain-containing integrins.
Seven of the integrin alpha subunits described to date, alpha 1, alpha 2, alpha L, alpha X, alpha d, alpha M and alpha E, contain a highly conserved I (or A) domain of approximately 200 amino acid residues inserted near the amino-terminus of the subunit. As the result of a variety of independent experimental approaches, a large body of data has recently accumulated that indicates that the I domains are independent, autonomously folding domains capable of directly binding ligands that play a necessary and important role in ligand binding by the intact integrins. Recent crystallographic studies have elucidated the structures of recombinant alpha M and alpha L I domains and also delineated a novel divalent cation-binding motif within the I domains (metal ion-dependent adhesion site, MIDAS) that appears to mediate the divalent cation binding of the I domains and the I domain-containing integrins to their ligands.
Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Dickeson
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Santoro
D000595:Amino Acid Sequence; D002413:Cations, Divalent / Q000378:metabolism; D017124:Conserved Sequence / Q000235:genetics; D006801:Humans; D016023:Integrins / Q000737:chemistry* / Q000502:physiology; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D002413:Cations, Divalent; D016023:Integrins; D008024:Ligands