A 50-kDa variant form of human surfactant protein D
| Autor: | Yoshio Kuroki, Eiji Matsuura, L D Nielsen, J H Freed, J M Shannon, Robert J. Mason |
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| Rok vydání: | 1998 |
| Předmět: |
Pulmonary and Respiratory Medicine
Glycosylation Protein subunit Pulmonary Fibrosis Size-exclusion chromatography Blotting Western Carbohydrates Pulmonary Alveolar Proteinosis chemistry.chemical_compound Medicine Humans Threonine Amino Acids Pulmonary Surfactant-Associated Protein D Glycoproteins chemistry.chemical_classification Molecular mass business.industry Surfactant protein D Pulmonary Surfactants Amniotic Fluid Molecular Weight chemistry Biochemistry Chromatography Gel business Glycoprotein Bronchoalveolar Lavage Fluid |
| Zdroj: | The European respiratory journal. 12(5) |
| ISSN: | 0903-1936 |
| Popis: | The dominant form of human surfactant protein D (SP-D) is a multimeric collagenous glycoprotein composed of monomeric subunits that have a molecular mass of 43 kDa under reducing conditions. However, in evaluating monoclonal antibodies to human SP-D, an additional monomeric subunit was identified with a reduced molecular mass of 50 kDa. This 50-kDa variant was detected in approximately half of the samples evaluated and was found in lavage fluid from normal subjects, patients with alveolar proteinosis or idiopathic pulmonary fibrosis and in amniotic fluid. This 50-kDa variant had the same amino-terminal sequence, amino acid composition and apparent size of the carboxy-terminal collagenase-resistant fragment (20 kDa) as the 43-kDa subunit. The major difference was in the amino-terminal portion of the molecule and was due to altered glycosylation, as determined by carbohydrate staining, chemical deglycosylation, treatment with N-glycanase and neuraminidase and reduced signals for threonine at positions 5, 9 and 10 during amino-terminal sequencing. After gel filtration chromatography, the 50-kDa form was not present in the high molecular weight fraction, which is commonly used in purification of SP-D, but was found only in the smaller molecular weight fraction of monomers and trimers of SP-D. In conclusion, the 50 kDa-form of surfactant protein D is produced by post-translational glycosylation and does not form higher ordered oligomers, but its precise physiological function remains to be determined. |
| Databáze: | OpenAIRE |
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