Folding of the N-terminal, ligand-binding region of integrin alpha-subunits into a beta-propeller domain.
The N-terminal approximately 440 aa of integrin alpha subunits contain seven sequence repeats. These are predicted here to fold into a beta-propeller domain. A homologous domain from the enzyme phosphatidylinositol phospholipase D is predicted to have the same fold. The domains contain seven four-stranded beta-sheets arranged in a torus around a pseudosymmetry axis. The trimeric G-protein beta subunit (G beta) appears to be the most closely related beta-propeller. Integrin ligands and a putative Mg2+ ion are predicted to bind to the upper face of the beta-propeller. This face binds substrates in beta-propeller enzymes and is used by the G protein beta subunit to bind the G protein alpha subunit. The integrin alpha subunit I domain, which is structurally homologous to the G protein alpha subunit, is tethered to the top of the beta-propeller domain by a hinge that may allow movement of the domains relative to one another. The Ca2+-binding motifs in integrin alpha subunits are on the lower face of the beta-propeller.
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Center for Blood Research and Harvard Medical School, Department of Pathology, Boston, MA 02115, USA.
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D004220:Disulfides; D005544:Forecasting; D016023:Integrins / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment
D004220:Disulfides; D016023:Integrins; D008024:Ligands