title: Crystal structure of the human leukocyte Fc receptor, Fc gammaRIIa.
abstract: Fc gamma receptors bind IgG to initiate cellular responses against pathogens and soluble antigens. We have determined the three-dimensional structure of the extracellular portion of human Fc gammaRIIa to 2.0 A resolution providing a structural basis for the unique functions of the leukocyte FcR family. The receptor is composed of two immunoglobulin domains and arranged to expose the ligand-binding site at one end of domain 2. Using alanine mutants we find that the binding sites for IgG1 and 2 are similar but the relative importance of specific regions on the receptor varies. In crystals, Fc gammaRIIa molecules associate to resemble V(L)V(H) dimers, suggesting that two Fc gammaRIIa molecules could cooperate to bind IgG in an asymmetric manner.
authors.affiliation: Biomolecular Research Institute, Parkville, Victoria, Australia.
authors.forename: K F
authors.initials: KF
authors.lastname: Maxwell
authors.forename: M S
authors.initials: MS
authors.lastname: Powell
authors.forename: M D
authors.initials: MD
authors.lastname: Hulett
authors.forename: P A
authors.initials: PA
authors.lastname: Barton
authors.forename: I F
authors.initials: IF
authors.lastname: McKenzie
authors.forename: T P
authors.initials: TP
authors.lastname: Garrett
authors.forename: P M
authors.initials: PM
authors.lastname: Hogarth
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D019556:COS Cells; D017124:Conserved Sequence; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007136:Immunoglobulins / Q000737:chemistry; D007962:Leukocytes / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017452:Receptors, IgG / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D015703:Antigens, CD; C080568:Fc gamma receptor IIA; D007074:Immunoglobulin G; D007136:Immunoglobulins; D008024:Ligands; D017452:Receptors, IgG