Tropoelastin Synthesis in Fetal Bovine Tissues

Tropoelastin was examined in bovine lung, aortic and ligament tissues using both organ culture and cell-free translation systems. The bovine tissues synthesized two tropoelastin polypeptides of approximately 70,000 and 68,000 daltons. Two polypeptides were also seen amongst the translation products directed by mRNAs isolated from each of the individual tissues. Both proteins were shown to be tropoelastins directly by immunoprecipitation with specific antibody and limited NH₂-terminal sequence analyses and indirectly by two-dimensional gel electrophoresis. The finding of two forms of tropoelastin is similar to that previously reported in chick tissues although the apparent molecular weights of the tropoelastins differ between the two species. Another interesting observation is that the proportion of the two tropoelastins differs amongst the three fetal tissues examined. This situation is similar to the differences seen in the ratio of tropoelastin a and b between embryonic chick lung and aortic tissues.