Key result
Cardiac tropomyosin from chick embryos consists of three polypeptides, with alpha 2 and alpha 3 likely derived from the primary translational product alpha 1 via posttranslational modifications.
This basic science study demonstrates that multiple forms of cardiac tropomyosin in chick embryos arise from posttranslational modifications of a single primary translational product.
Chick embryo data warrant no clinical changes; extends tropomyosin biosynthesis knowledge but leaves open mammalian and human relevance.
Cardiac tropomyosin from 20-day-old chick embryos is composed of three different polypeptides with the same molecular weight but different isoelectric points. These polypeptides, which are designated as alpha 1, alpha 2, and alpha 3, have identical peptide maps. In vitro, however, only polypeptide alpha 1 is synthesized in a reticulocyte lysate programmed with cardiac RNA. These results, together with the observations indicating that tropomyosin alpha 2 corresponds to a phosphorylated polypeptide, suggest that only tropomyosin alpha 1 corresponds to a primary translational product and that forms alpha 2 and alpha 3 are derived from alpha 1 as a consequence of posttranslational modifications.
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Palmer et al. (1982) studied this question. Cardiac tropomyosin from chick embryos consists of three polypeptides, with alpha 2 and alpha 3 likely derived from the primary translational product alpha 1 via posttranslational modifications.
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