Immunologic identification of a pulmonary surfactant-associated protein of molecular weight = 6000 daltons.
Hydrophobic, small molecular weight, surfactant-associated protein of Mr = 6000 (SAP-6) was isolated from bovine, canine, and human alveolar lavage and identified by silver staining after sodium dodecyl sulfate polyacrylamide gel electrophoresis gels. Lesser amounts of protein of Mr = 14,000, 20,000, and 26,000 daltons also copurified with SAP-6, likely representing oligomers of the Mr = 6,000 dalton protein. In the absence of sulfhydryl-reducing agents, increased amounts of the larger forms of the protein were observed. Antisera generated against bovine SAP-6 were used to further characterize the protein and distinguish it from the more abundant surfactant-associated glycoprotein of Mr = 35,000 (SAP-35) present in mammalian surfactants. Rabbit antisera generated against the bovine hydrophobic protein recognized SAP-6 and lesser amounts of the proteins of Mr = 14,000, 20,000, and 26, 000 daltons. The SAP-6 antisera were reactive against the hydrophobic proteins from human, bovine, and canine surfactants as assessed by immunoblot analysis after sodium dodecyl sulfate polyacrylamide gel electrophoresis. SAP-6 antisera did not detect bovine SAP-35 the abundant surfactant-associated glycoprotein, by immunoblot analysis; however, some reactivity of the anti-SAP-6 was detected against purified bovine SAP-35 by a sensitive enzyme-linked immune-adsorbant assay. Anti-SAP-6-did not react with bovine serum components either by immunoblot or by enzyme-linked immune-adsorbant assay. Monospecific antisera generated against bovine SAP-35 did not detect SAP-6 by immunoblot analysis.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D002417:Cattle; D004285:Dogs; D006801:Humans; D007163:Immunosorbent Techniques; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis / Q000276:immunology; D011510:Proteolipids / Q000276:immunology* / Q000302:isolation & purification; D037662:Pulmonary Surfactant-Associated Protein A / Q000031:analogs & derivatives*; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000276:immunology* / Q000302:isolation & purification; D012995:Solubility; D013045:Species Specificity
D010446:Peptide Fragments; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C445842:SFTPA1 protein, human