Structure-function relationships of bovine pulmonary surfactant proteins: SP-B and SP-C.
Pulmonary surfactant contains at least three unique proteins: SP-A, SP-B and SP-C. SP-B and SP-C from bovine surfactant are markedly hydrophobic and have molecular masses between 3 and 26 kDa. We identify surfactant proteins under nonreducing conditions on polyacrylamide gels with approximate molecular mass of 5, 14, 26 kDa (SP-5, 14, 26) when organic solvent-soluble material is eluted from a Sephadex LH-20 size exclusion column followed by separation on a high-performance reverse-phase chromatography system. These bands correspond to monomeric SP-C, oligomeric SP-C and oligomeric SP-B, respectively. Computer analysis (Eisenberg-hydrophobic moment) of sequences for these proteins suggests that SP-B contains surface-seeking amphiphilic segments. In contrast, SP-C resembles a more hydrophobic transmembrane anchoring peptide. Dispersions containing dipalmitoylphosphatidylcholine, phosphatidylglycerol, palmitic acid and multimeric SP-B and SP-C duplicate the surface activity of natural surfactant when assayed in a pulsating bubble surfactometer. We speculate that oligomers of SP-B and monomers and oligomers of SP-C may act cooperatively in affecting surfactant function. An important function of SP-B and SP-C may be to affect the ordering of surfactant lipids so that rates of transport of surfactant lipids to the hypophase surface in the alveoli are enhanced.
Takahashi
A
A
Department of Pediatrics, King/Drew Medical Center, Los Angeles, CA 90059.
Waring
A J
AJ
Amirkhanian
J
J
Fan
B
B
Taeusch
H W
HW
D000595:Amino Acid Sequence; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004578:Electron Spin Resonance Spectroscopy; D001330:Electronic Data Processing; D004591:Electrophoresis, Polyacrylamide Gel; D008055:Lipids / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011510:Proteolipids; D011663:Pulmonary Surfactants; D013329:Structure-Activity Relationship
D008055:Lipids; D011510:Proteolipids; D011663:Pulmonary Surfactants