title: Subunit association and conformational flexibility in the head subdomain of human CD81 large extracellular loop.
abstract: The large extracellular loop of human CD81, a tetraspanin mediating hepatitis C virus envelope protein E2 binding to human cells, has been crystallized in a hexagonal form. The three-dimensional structure, solved and refined at 2.6 A resolution (R-factor = 22.8%), shows that the protein adopts a dimeric assembly, based on an association interface built up by tetraspanin-conserved residues. Structural comparisons with the tertiary structure of human CD81 large extracellular loop, previously determined in a different crystal form, show marked conformational fluctuations in the molecular regions thought to be involved in binding to the viral protein, suggesting rules for recognition and assembly within the tetraspan web.
authors.affiliation: Department of Physics-INFM, Center of Excellence for Biomedical Research, University of Genoa, Italy.
authors.forename: Kengo
authors.initials: K
authors.lastname: Kitadokoro
authors.forename: Marco
authors.initials: M
authors.lastname: Ponassi
authors.forename: Giuliano
authors.initials: G
authors.lastname: Galli
authors.forename: Roberto
authors.initials: R
authors.lastname: Petracca
authors.forename: Fabiana
authors.initials: F
authors.lastname: Falugi
authors.forename: Guido
authors.initials: G
authors.lastname: Grandi
authors.forename: Martino
authors.initials: M
authors.lastname: Bolognesi
mesh_terms: D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D016174:Hepacivirus / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018583:Pliability; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D060225:Tetraspanin 28
chemical_list: D015703:Antigens, CD; C554798:CD81 protein, human; D008565:Membrane Proteins; D060225:Tetraspanin 28