Requirement of the collagenous domain for carbohydrate processing and secretion of a surfactant protein, SP-A

Michael A. O'Reilly, Lawrence Nogee, Jeffrey A. Whitsett

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31 Scopus citations


Two distinct intracellular forms of surfactant protein Mr = 35 000 (SP-A) were demonstrated in both purified type II epithelial cells and rat lung in vivo. High-mannose precursors of Mr = 30 000 and 34 000 comprised a significant fraction of intracellular SP-A in vivo and in vitro. A second intracellular pool was demonstrated in lamellar body enriched fractions which contained endoglycosidase-H resistant, sialylated forms of SP-A. Intracellular transport and secretion of SP-A was not altered by inhibitors of carbohydrate processing. However, incubation of type II cells with α,α′-dipyridyl or cis-4-hydroxy-l-proline, agents which disrupt triple-helix formation within collagenous peptide domains, inhibited sialylation, intracellular transport to the lamellar body fraction and secretion. In the presence of either α,α′-dipyridyl or cis-4-hydroxy-l-proline, high mannose precursors accumulated intracellularly and were not secreted after 16-18 h. Thus, high-mannose precursors in proximal intracellular pool(s) and sialylated forms in lamellar body-enriched fractions represent two major intracellular storage forms of SP-A in vitro and in vivo. SP-A is routed by processes dependent upon the hydroxylation of the collagenous domain of the polypeptide. Transport and secretion of SP-A are not dependent upon the addition or processing of asparagine-linked carbohydrate.

Original languageEnglish (US)
Pages (from-to)176-184
Number of pages9
JournalBBA - Molecular Cell Research
Issue number2
StatePublished - Apr 25 1988
Externally publishedYes


  • (Lamellar body)
  • Collagenous domain
  • Glycosylation
  • Surfactant protein

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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