title: Crystal structure of the extracellular domain of a human Fc gamma RIII.
abstract: Fc receptors play a major role in immune defenses against pathogens and in inflammatory processes. The crystal structure of a human immunoglobulin receptor, FcgammaRIIIb, has been determined to 1.8 A resolution. The overall fold consists of two immunoglobulin-like domains with an acute interdomain hinge angle of approximately 50 degrees. Trp-113, wedged between the N-terminal D1 and the C-terminal D2 domains, appears to further restrict the hinge angle. The putative Fc binding region of the receptor carries a net positive charge complementary to the negative-charged receptor binding regions on Fc. A 1:1 binding stoichiometry between the receptor and Fc was measured by both the equilibrium and nonequilibrium size-exclusion chromatography. Two separate parallel dimers are observed in the crystal lattice, offering intriguing models for receptor aggregation.
authors.affiliation: Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77555, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: C C
authors.initials: CC
authors.lastname: Boesen
authors.forename: S
authors.initials: S
authors.lastname: Radaev
authors.forename: A G
authors.initials: AG
authors.lastname: Brooks
authors.forename: W H
authors.initials: WH
authors.lastname: Fridman
authors.forename: C
authors.initials: C
authors.lastname: Sautes-Fridman
authors.forename: P D
authors.initials: PD
authors.lastname: Sun
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002850:Chromatography, Gel; D017124:Conserved Sequence; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D005110:Extracellular Space / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017452:Receptors, IgG / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D007128:Immunoglobulin Fragments; D008024:Ligands; D009842:Oligopeptides; D017452:Receptors, IgG