Characterization of IgC receptors of the fetal rabbit yolk sac membrane: localization to subcellular fraction and effects of chemical agents and enzymes on binding.
Previous studies have established the existence of IgG receptors on the endodermal cells of the fetal rabbit yolk sac membrane (YSM). The present study partially characterizes these cell-associated receptors. The specific binding of rabbit IgG (IgGR) to freshly prepared cell homogenates, nuclei-free brush border preparations, and plasma membrane-rich fractions confirms that receptor function is associated with the endodermal cell, and indicates that this function is localized on its apical brush border, specifically on its plasma membrane. The protein nature of the receptor is demonstrated by the loss of specific binding capacity after treatment of formalin-fixed YSM with papain and trypsin. Evidence has also been adduced which indicates that membrane carbohydrate is not involved in receptor function. Thus, treatment of YSM with neuraminidase, beta-galactosidase, mixed glycosidases, as well as oxidation of YSM with periodate all are without effect on its capacity to bind IgGR. The interaction of IgGR with the receptor elements of formalin-fixed YSM is partially ionic in character. NaCl reversibly inhibits binding of IbGR by 60%. Divalent ions such as Ca++ are not involved in this receptor-ligand interaction since EDTA-treated YSM binds IgGR to the same extent as do controls. Receptor material on fixed YSM resists extraction by non-ionic detergents, deoxycholate, and chaotropic agents.
D000818:Animals; D001665:Binding Sites; D002458:Cell Fractionation; D002462:Cell Membrane / Q000276:immunology; D005260:Female; D005696:Galactosidases / Q000494:pharmacology; D006026:Glycoside Hydrolases / Q000494:pharmacology; D007074:Immunoglobulin G; D007784:Lactoperoxidase / Q000494:pharmacology; D009439:Neuraminidase / Q000494:pharmacology; D010206:Papain / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000494:pharmacology; D011817:Rabbits; D012965:Sodium Chloride / Q000494:pharmacology; D014817:Vitelline Membrane / Q000276:immunology*
D007074:Immunoglobulin G; D012965:Sodium Chloride; D007784:Lactoperoxidase; D005696:Galactosidases; D006026:Glycoside Hydrolases; D009439:Neuraminidase; D010447:Peptide Hydrolases; D010206:Papain