Biochemical properties of phosphatidylcholine-binding proteins that share common antigenic determinants with Fc gamma 2b receptor.
Biochemical and immunological properties of biosynthetically radiolabeled phosphatidylcholine-(PC-) binding proteins were investigated. The PC-binding proteins were extracted from the detergent lysate of biosynthetically radiolabeled P388D1 cells by affinity chromatography on PC-Sepharose and filtered through a Sephadex G-100 gel column in the presence of 6 M urea. Isoelectric focusing of the gel-filtered materials in the presence of 6 M urea revealed the presence of a major protein component of pIe of 5.8 and minor heterogeneous cellular proteins. The yield of the electrofocused PC-binding proteins based on protein determination by Lowry's method ranged from 0.7 to 4 mg per 10(9) cells. The purified PC-binding proteins appeared to be tightly associated with Triton X-100 and phospholipids in the weight ratio of 0.57 and 0.05 g/g of proteins, respectively. The majority of lipids that could be extracted from the PC-binding proteins by chloroform/methanol (2:1 v/v) are free fatty acids, whereas lipids extracted from Pronase-treated PC-binding proteins contained phosphatidylethanolamine. By amino acid analysis, the purified PC-binding proteins were found to consist of a minimum of 417 amino acid residues, suggesting a minimum molecular weight of about 38 000 for this protein. Results of radiolabeling experiments with [3H]glucosamine and amino acid analysis both showed the presence of a mole of glucosamine per a mole of the PC-binding proteins, suggesting their glycoprotein nature. About 40% of the purified PC-binding proteins coprecipitated with monoclonal anti-Fc gamma 2bR antibody (2.4G2) in detergent-containing buffer, whereas only 6% of the isolated IgG binding proteins reacted with this antibody.(ABSTRACT TRUNCATED AT 250 WORDS)
Fernandez-Botran
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Suzuki
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D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000911:Antibodies, Monoclonal; D002846:Chromatography, Affinity; D003902:Detergents; D000939:Epitopes / Q000032:analysis*; D007074:Immunoglobulin G; D007525:Isoelectric Focusing; D007941:Leukemia P388 / Q000378:metabolism; D051379:Mice; D017830:Octoxynol; D010713:Phosphatidylcholines / Q000378:metabolism*; D010743:Phospholipids / Q000032:analysis; D011092:Polyethylene Glycols; D011961:Receptors, Fc / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D017452:Receptors, IgG; D014316:Tritium
D000596:Amino Acids; D000911:Antibodies, Monoclonal; D003902:Detergents; D000939:Epitopes; D007074:Immunoglobulin G; D010713:Phosphatidylcholines; D010743:Phospholipids; D011961:Receptors, Fc; D017452:Receptors, IgG; D014316:Tritium; D011092:Polyethylene Glycols; D017830:Octoxynol