Differential partitioning of pulmonary surfactant protein SP-A into regions of monolayers of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylglycerol.
The interaction of the pulmonary surfactant protein SP-A fluorescently labeled with Texas Red (TR-SP-A) with monolayers of dipalmitoylphosphatidylcholine (DPPC) and DPPC/dipalmitoylphosphatidylglycerol 7:3 w/w has been investigated. The monolayers were spread on aqueous subphases containing TR-SP-A. TR-SP-A interacted with the monolayers of DPPC to accumulate at the boundary regions between liquid condensed (LC) and liquid expanded (LE) phases. Some TR-SP-A appeared in the LE phase but not in the LC phase. At intermediate surface pressures (10-20 mN/m), the protein caused the occurrence of more, smaller condensed domains, and it appeared to be excluded from the monolayers at surface pressure in the range of 30-40 mN/m. TR-SP-A interaction with DPPC/dipalmitoylphosphatidylglycerol monolayers was different. The protein did not appear in either LE or LC but only in large aggregates at the LC-LE boundary regions, a distribution visually similar to that of fluorescently labeled concanavalin A adsorbed onto monolayers of DPPC. The observations are consistent with a selectivity of interaction of SP-A with DPPC and for its accumulation in boundaries between LC and LE phase.
Ruano
M L
ML
Departmento de Bioquímica, Facultad de Biología, Universidad Complutense, Madrid, Spain.
Nag
K
K
Worthman
L A
LA
Casals
C
C
Pérez-Gil
J
J
Keough
K M
KM
D015060:1,2-Dipalmitoylphosphatidylcholine; D009327:4-Chloro-7-nitrobenzofurazan / Q000031:analogs & derivatives; D000345:Affinity Labels; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D003208:Concanavalin A; D007700:Kinetics; D008081:Liposomes; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D011312:Pressure; D011510:Proteolipids / Q000737:chemistry* / Q000378:metabolism*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013499:Surface Properties; D013552:Swine; D014966:Xanthenes
C078632:1-acyl-2-(12-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl)phosphatidylcholine; D000345:Affinity Labels; D008081:Liposomes; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D014966:Xanthenes; D003208:Concanavalin A; D015060:1,2-Dipalmitoylphosphatidylcholine; C034657:Texas red; D009327:4-Chloro-7-nitrobenzofurazan; C030345:1,2-dipalmitoylphosphatidylglycerol