Tropomyosin was quantitated in embryonic and postembryonic chick leg muscle by a procedure involving acrylamide gel electrophoresis, with subsequent elution of tropomyosin from the gels, followed by adsorption on membrane filters and subsequent extraction and spectrophotometric determination of a dye-tropomyosin complex. Tropomyosin was present at low levels of 20 mg/100 g muscle at 11 days of incubation and increased to 360 mg/100 g muscle at 2 months of development. The accumulation data for tropomyosin parallel those of myosin throughout development. Chicken tropomyosin in the presence of unfractionated chicken troponin (troponin A and B) confers EGTA sensitivity to Mg2+-activated desensitized actomyosin. The presence of troponin B activity in the unfractionated preparation is evident since the troponin preparation in the absence of tropomyosin inhibits superprecipitation of Mg2+-activated desensitized actomyosin. In this respect chick tropomyosin and troponin are similar to the corresponding rabbit protein.
ASJC Scopus subject areas
- Molecular Biology