Characterization of cell matrix associated collagens synthesized by aortic endothelial cells in culture

Several collagen types have been isolated and characterized from bovine aortic endothelial cells and their associated extracellular matrix. Two collagens, which comigrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the alpha 1(III), alpha 1(V), and alpha 2(V) collagen chains, were isolated by salt precipitation from pepsin digests of cell layer proteins. Two of these chains were further purified by molecular-sieve and ion-exchange chromatography and were identified as alpha 1(III) and alpha 1(V) by one-dimensional peptide maps generated with mast cell protease and cyanogen bromide. In contrast to type III collagen, which was found in both the culture medium and cell layer, type V collagen appeared to be restricted to the cell layer. In addition to their occurrence as cell layer constituents, both types III and V collagens were localized to an extracellular matrix after the cells had been removed from the culture dishes by detergent. Preliminary studies based on peptide maps comparing type III collagen from the cell layer and culture medium provide evidence for structural heterogeneity within this collagen type.