title: Structural studies of Fc receptors. III. Isolation and molecular weight analysis of the component chain of Fc gamma receptor of macrophage.
abstract: Surface receptors of guinea pig peritoneal macrophages specific for the Fc region of IgG (Fc gamma receptor) were isolated and identified as a surface-radioiodinated component with a molecular weight of 44,000 that bound in an Fc-specific manner to IgG2 of guinea pig immunoglobulin immobilized in any of the following three different ways: IgG2 antibody in insoluble immune complex, IgG2 antibody bound to antigen-coupled Sepharose, and IgG2 covalently coupled to Sepharose. In order to obtain the Fc gamma receptor retaining the binding activity, the Fc-binding component was isolated by IgG2 affinity chromatography in which mild acidic buffer (pH 5.0-4.0) was chosen to elute the component bound to the affinity column. Forty-five to sixty-two percent of the eluted radioactivity was shown to rebind to the IgG2-affinity column. The bound fraction showed a single radioactive peak of 44,000 daltons in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Fc-binding component isolated by the affinity chromatography behaved similarly in gel filtration in the presence of a detergent, as did the detergent-solubilized Fc gamma receptor before isolation by affinity chromatography. These results suggested that the Fc gamma receptor was isolated in a native form. Furthermore, it was confirmed that the isolated Fc gamma receptor is distinct from actin or the actin-like protein (DNase I-binding protein) which had been reported to bind to IgG-affinity column.
mesh_terms: D000818:Animals; D002846:Chromatography, Affinity / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D006168:Guinea Pigs; D007074:Immunoglobulin G; D046911:Macromolecular Substances; D008264:Macrophages / Q000276:immunology*; D008970:Molecular Weight; D011961:Receptors, Fc / Q000302:isolation & purification*; D017452:Receptors, IgG
chemical_list: D007074:Immunoglobulin G; D046911:Macromolecular Substances; D011961:Receptors, Fc; D017452:Receptors, IgG