Human placentae membrane receptor for IgG—i. Studies on properties and solubilization of the receptor
| Autor: | Małgorzata Niezgódka, Janusz Boratyński, Mikulska J, Józef Lisowski, Maciej Ugorski |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
Placenta
Proteolysis Immunology Fc receptor Receptors Fc Antibody Specificity Cell surface receptor medicine Humans Receptor Molecular Biology Polyacrylamide gel electrophoresis Glycoproteins medicine.diagnostic_test biology Molecular mass Phospholipase C Chemistry Cell Membrane Temperature Hydrogen-Ion Concentration Trypsin Solutions Biochemistry Immunoglobulin G Pronase Type C Phospholipases biology.protein medicine.drug |
| Zdroj: | Molecular Immunology. 18:163-172 |
| ISSN: | 0161-5890 |
| DOI: | 10.1016/0161-5890(81)90082-1 |
| Popis: | Characterization of the human placental membrane receptor for human 125 I-IgG is described. The receptor bound specifically both monomers and aggregates of human IgG. Human colostral IgA, bovine, sheep, pig, and horse IgG were not bound. No effect of pH in the range 6.6–7.4, ionic strength in the range 0.1–0.5, and temperature between 4 and 45°C on the binding was found. A water-soluble fraction containing the active receptor (glycoprotein fraction-PGP) was obtained from the placental membranes using lithium diiodosalicylate. The solubilized receptor interacted with IgG better at 4°C than at 20°C or 37°C. The results on replacement of monomeric IgG by aggregated IgG, and vice versa, suggest that both monomers and aggregates of human IgG, were bound to the same receptor sites. The apparent association constant for monomeric human IgG was 0.86 ± 0.2 × 10 7 mole −1 , and 2.0 ± 0.16 × 10 15 IgG molecules were bound per l mg of the membrane protein. Formaldehyde (0.1%), 2-mercaptoethanol (50 m M ), and periodate (4 m M ) showed no effect on the binding properties of the membrane-bound and on the solubilized receptor, as well. Higher concentrations of periodate (10 m M or 20 m M ) decreased the binding of IgG to membranes but showed no effect on the water-soluble receptor. Both the membrane-bound and the solubilized receptor were sensitive to papain. Pronose abolished the receptor activity after prolonged proteolysis only. Neuraminidase did not affect the activity of the receptor. The decrease of the binding activity of the membrane-bound receptor by trypsin and phospholipase C was due to a release of a material containing an active receptor. No effect of trypsin or phospholipase C on the activity of solubilized receptor was observed. The results obtained suggest a protein character of the placental Fc receptor. After electrophoresis of 125 I-labeled solubilized receptor in polyacrylamide gel in the presence of SDS, 2 major protein peaks with molecular weights of 74,000 and 104,000 and 3 minor peaks with molecular weights of 56,000, 144,000, and 163,000 were found. |
| Databáze: | OpenAIRE |
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