Binding of pulmonary surfactant protein A to galactosylceramide and asialo-GM2.
The binding of pulmonary surfactant protein A (SP-A) to glycolipids was examined in the present study. The direct binding of SP-A on a thin-layer chromatogram was visualized using 125I-SP-A as a probe. 125I-SP-A bound to galactosylceramide and asialo-GM2, but failed to exhibit significant binding to GM1, GM2, asialo-GM1, sulfatide, and Forssman antigen. The study of 125I-SP-A binding to glycolipids coated onto microtiter wells also revealed that SP-A bound to galactosylceramide and asialo-GM2. SP-A bound to galactosylceramides with non-hydroxy or hydroxy fatty acids, but showed no binding to either glucosylceramide or galactosylsphingosine. Excess native SP-A competed with 125I-SP-A for the binding to asialo-GM2 and galactosylceramide. Specific antibody to rat SP-A inhibited 125I-SP-A binding to glycolipids. In spite of chelation of Ca2+ with EDTA or EGTA, SP-A retained a significant binding to glycolipids. Inclusion of excess monosaccharides in the binding buffer reduced the glycolipid binding of SP-A, but failed to achieve complete abolishment. The oligosaccharide isolated from asialo-GM2 is also effective at reducing 125I-SP-A binding to the solid-phase asialo-GM2. From these data, we conclude that SP-A binds to galactosylceramide and asialo-GM2, and that both saccharide and ceramide moieties in the glycolipid molecule are important for the binding of SP-A to glycolipids.
Kuroki
Y
Y
Department of Biochemistry, Sapporo Medical College, Japan.
Gasa
S
S
Ogasawara
Y
Y
Makita
A
A
Akino
T
T
D000818:Animals; D002240:Carbohydrate Sequence; D002413:Cations, Divalent; D005699:Galactosylceramides / Q000378:metabolism*; D005732:Gangliosides; D006028:Glycosphingolipids / Q000378:metabolism*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D011485:Protein Binding; D011510:Proteolipids / Q000378:metabolism*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002413:Cations, Divalent; D005699:Galactosylceramides; D005732:Gangliosides; D006028:Glycosphingolipids; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C038244:ganglio-N-triaosylceramide