The major lung surfactant protein, SP 28-36, is a calcium-dependent, carbohydrate-binding protein.
SP 28-36, a major protein of pulmonary surfactant, has striking amino acid sequence homology with soluble mannose-binding proteins isolated from rat liver and contains residues common to the carbohydrate-binding domains of other mammalian lectins. We have used carbohydrate-affinity chromatography to investigate carbohydrate-binding properties of SP 28-36 isolated from canine and human (alveolar proteinosis patients) lung lavage. SP 28-36 binds to immobilized D-mannose, L-fucose, D-galactose, and D-glucose. The protein binds only weakly to N-acetyl-D-galactosamine and N acetyl-D-glucosamine. Binding is Ca2+-dependent. The threshold Ca2+ concentration is 0.6 mM and maximal binding occurs with 1 mM Ca2+. Bound protein is quantitatively recovered by elution with 2 mM EDTA. Ba2+, Sr2+, and Mn2+, but not Mg2+, can substitute for Ca2+. Unlike some other mammalian lectins, SP 28-36 binds to carbohydrate at pH 5.0. Recombinant human SP 28-36 isolated from the media of Chinese hamster ovary cells, transfected with a DNA construct encoding SP 28-36, has similar carbohydrate-binding activity to the native proteins. Mannose affinity chromatography of the culture medium of Chinese hamster ovary cells results in an efficient purification of the secreted recombinant human SP 28-36.
Haagsman
H P
HP
Cardiovascular Research Institute, University of California, San Francisco 94143.
Hawgood
S
S
Sargeant
T
T
Buckley
D
D
White
R T
RT
Drickamer
K
K
Benson
B J
BJ
D000818:Animals; D001059:Apoproteins / Q000302:isolation & purification / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent; D002460:Cell Line; D002846:Chromatography, Affinity / Q000379:methods; D004492:Edetic Acid / Q000494:pharmacology; D006601:Hexoses / Q000378:metabolism*; D007700:Kinetics; D003012:Microbial Collagenase; D011485:Protein Binding; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000302:isolation & purification / Q000378:metabolism*
D001059:Apoproteins; D002413:Cations, Divalent; D006601:Hexoses; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C046616:pulmonary surfactant apoprotein; D004492:Edetic Acid; D003012:Microbial Collagenase; D002118:Calcium