Collagen-binding proteins secreted by type II pneumocytes in culture

Edmond Crouch, William Longmore

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


The alveolar epithelial basement membrane is believed to play important roles in lung development, in maintaining normal alveolar architecture, and in guiding repair following lung injury. However, little is known about the formation of this structure, or of the mechanisms which mediate interactions between the epithelium and specific matrix macromolecules. Since type IV collagen is a major structural component of basement membranes, we investigated the production of type IV collagen-binding proteins by primary cultures of rat lung type II pneumocytes. Cultures were labeled for up to 24 h with 3H-labeled amino acids or [3H]mannose. Soluble collagen-binding proteins which accumulated in the culture medium were isolated by chromatography on collagen-Sepharose and examined by SDS-polyacrylamide gel electrophoresis. The major type IV collagen-binding protein (CBP1) was identified as fibronectin. We also identified a novel disulfide-bonded collagen-binding glycoprotein (CBP2; Mr = 45 000, reduced). This protein was not recognized by polyclonal antibodies to fibronectin, and showed no detectable binding to denatured type I collagen. The protein was resolved from fibronecti and partially purified by sequential chromatography on gelatin and type IV collagen-Sepharose. We suggest that type II pneumocyte-derived collagen-binding proteins contribute to the formation of the epithelial basement membrane and/or mediate the attachment of these cells to collagenous components of the extracellular matrix.

Original languageEnglish
Pages (from-to)81-86
Number of pages6
JournalBBA - General Subjects
Issue number1
StatePublished - Apr 16 1987


  • (Type II cell)
  • Fibronecitin
  • Pulmonary epithelial cell
  • Type IV collagen


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