Amphipathic lipid-bound protein antigens in mouse bladder carcinomas detected by a monoclonal antibody.
We have found organic solvent soluble proteins that contain tightly bound fatty acids. They were demonstrated in mouse bladder carcinomas by a monoclonal rat antibody, 33E7C. The antigens recognized by antibody 33E7C copurified with lipids when extracted from bladder carcinomas with a mixture of chloroform-methanol. The antigens remained in the chloroform phase after solvent partition with water. Chromatographic analysis using an alpha-hydroxy-propylated Sephadex G-50 (LH60) column led to the isolation of a group of proteins binding to antibody 33E7C. Four proteins (10K, 18K, 25K, and 40K daltons) were found on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) after radioimmunoprecipitation with antibody 33E7C. After preparative SDS-PAGE, the purified antigens were soluble in both water and a mixture of chloroform-methanol (2:1) but were freed from phospholipids and glycolipids. The antigens have been characterized by the presence of tightly bound fatty acids with the following findings: (1) They were metabolically colabeled by incubating bladder carcinoma cells with [9,10-3H]palmitic acid and [14C]leucine, followed by radioimmunoprecipitation assay and by SDS-PAGE. (2) After hydrolysis of proteins in NaOH-methanol, [3H]palmitic acid methyl ester was separated from the 40K and 18K proteins by thin-layer chromatography.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D000951:Antigens, Neoplasm / Q000032:analysis* / Q000276:immunology; D002725:Chloroform; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000378:metabolism*; D007163:Immunosorbent Techniques; D007930:Leucine / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D011506:Proteins / Q000276:immunology* / Q000378:metabolism; D051381:Rats; D012995:Solubility; D001749:Urinary Bladder Neoplasms / Q000276:immunology*; D014867:Water
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D005227:Fatty Acids; D010169:Palmitic Acids; D011506:Proteins; D014867:Water; D019308:Palmitic Acid; D002725:Chloroform; D007930:Leucine