Hepatocellular localisation of biosynthesis of vitronectin. Characterisation of the primary structure of rat vitronectin.

To characterize the primary structure of rat Vn, a cDNA library constructed from freshly isolated rat hepatocytes, was screened with a human Vn cDNA probe. Comparison of the sequence of the obtained rat cDNA clone with the sequences of human, mouse and rabbit Vn cDNA's showed predominantly consensus in the somatomedin B domain, the RGD-sequence and its flanking regions, in the first hemopexin type domain and at the carboxyl terminal part of Vn, the heparin binding site. To specify the liver cell type involved in the biosynthesis of Vn, we used a competitive PCR-assay to discriminate between expression levels. We found that expression of Vn in hepatocytes is at least 1000-fold higher than in Kupffer cells and 3000-fold higher than in endothelial liver cells.