Shedding of the guinea pig peritoneal macrophage Fc gamma receptor. Effect on apparent association constant and on the number of IgG-binding sites on the cells.
During our studies on the structure and properties of guinea pig peritoneal macrophage Fc gamma receptor we observed that these cells spontaneously release an IgG-binding material into supernatant. Although the shedding was accompanied by a decrease in IgG-binding ability of macrophages, the number of IgG-binding sites/cell before and after shedding was similar. However, macrophages after the shedding interacted with IgG with a lower apparent association constant, Ka. Therefore, we assume that the decrease of IgG-binding ability of cells was an effect of decrease in value of Ka. Experiments with protein synthesis inhibitors showed that the shed receptor is replaced by "de novo" synthesized receptor molecules.
Gorczyca
W
W
Department of Immunochemistry, Polish Academy of Sciences, Wrocław.
Janusz
M
M
Wieczorek
Z
Z
Lisowski
J
J
D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism*; D001202:Ascitic Fluid / Q000166:cytology; D001665:Binding Sites; D006168:Guinea Pigs; D007074:Immunoglobulin G / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008264:Macrophages / Q000276:immunology*; D011961:Receptors, Fc / Q000378:metabolism*; D017452:Receptors, IgG
D000943:Antigens, Differentiation; D007074:Immunoglobulin G; D011961:Receptors, Fc; D017452:Receptors, IgG