Identification of multiple tropoelastins secreted by bovine cells.
High resolution gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis, cell-free translation, and elastin-specific antibodies were used to identify three tropoelastin isoforms secreted by bovine tissue and cells. Tropoelastin isolated from nuchal ligament and from conditioned culture medium or cell-matrix extracts of ligament fibroblasts and auricular chondrocytes resolved as three distinct bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with molecular weights of approximately 67,500 (tropoelastin I), 65,000 (tropoelastin II), and 62,000 (tropoelastin III). Three tropoelastin polypeptides with molecular mass 2-3 kDa higher than their corresponding tissue forms were also evident in cell-free translation products of ligamentum nuchae RNA, suggesting that each tropoelastin species is encoded by a unique mRNA. The presence of cysteine in all three tropoelastin isoforms was demonstrated by the incorporation of [35S]cysteine into newly synthesized tropoelastin polypeptides and by immunoreactivity with an antibody raised against a synthetic peptide that defines the cysteine-containing carboxyl-terminal region of tropoelastin. Immunological co-localization of the carboxyl-terminal antibody with insoluble elastin in lung vasculature and parenchyma suggests that intact tropoelastin and not a processed form is incorporated into the elastin fiber.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002474:Cell-Free System; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000032:analysis; D004549:Elastin / Q000031:analogs & derivatives* / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000032:analysis; D008168:Lung / Q000032:analysis; D008970:Molecular Weight; D012313:RNA / Q000378:metabolism; D014333:Tropoelastin / Q000378:metabolism*
D000596:Amino Acids; D000939:Epitopes; D014333:Tropoelastin; D012313:RNA; D004549:Elastin; D003545:Cysteine