Related Experiment Videos
Surfactant protein D is a divalent cation-dependent carbohydrate-binding protein
1Department of Pathology, Jewish Hospital, Washington University Medical Center, St. Louis, Missouri 63110.
The Journal of Biological Chemistry
|April 5, 1990
Summary
Surfactant protein D (SP-D) binds to specific sugars, particularly alpha-glucosyl residues, in a calcium-dependent manner. This lectin-like interaction explains how SP-D associates with lung surfactant.
Area of Science:
- Biochemistry
- Pulmonary Biology
- Glycobiology
Background:
- Surfactant protein D (SP-D) is a glycoprotein produced by lung type II epithelial cells.
- SP-D is known to interact with saccharides, facilitating its association with lung surfactant.
Purpose of the Study:
- To investigate the in vitro carbohydrate-binding properties of purified SP-D.
- To elucidate the specific carbohydrate interactions mediating SP-D's role in lung surfactant.
Main Methods:
- Utilized indirect immunoassays with saccharide-substituted bovine serum albumin (BSA) neoglycoproteins to quantify SP-D binding.
- Employed solution-phase polyethylene glycol precipitation assays to assess high-affinity binding.
- Investigated the effect of various saccharides and EDTA on SP-D binding.
Main Results:
- SP-D demonstrated specific, calcium-dependent binding to alpha-D-glucosidophenyl isothiocyanate-BSA and maltosyl-BSA.
- Binding was inhibited by alpha-glucosyl-containing saccharides like maltose and isomaltose.
- SP-D exhibited quantitative binding to maltosyl-agarose, with elution by maltose or EDTA.
Conclusions:
- SP-D functions as a calcium-dependent lectin with specificity for alpha-glucosyl residues.
- Carbohydrate-dependent interactions, particularly with alpha-glucosyl moieties, mediate the association of SP-D with lung surfactant.