Troponin-like proteins from muscles of the scallop, Aequipecten irradians.
Ca2+ regulation of molluscan actomyosin adenosine triphosphatase is known to be associated with the myosin molecule. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, however, also suggests the possible presence of troponin, a thin-filament-linked Ca2+-regulatory complex. In the present study, scallop troponin and tropomyosin were prepared and complexed with rabbit actin; the resulting synthetic thin filaments form a Ca2+-dependent actomyosin adenosine triphosphatase with Ca2+-insensitive rabbit myosin, indicating that the troponin in scallops is potentially functional. Scallop troponin I was isolated and mixed with chicken troponin C and troponin T, forming a functional hybrid troponin complex, indicating that scallop and vertebrate troponins may act by a common mechanism. Densitometry of sodium dodecyl sulphate/polyacrylamide gels reveals that in synthetic thin filaments there are larger amounts of troponin than are present in native thin filaments. Amounts present in the intact muscle were not determined.
D000199:Actins; D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D008974:Mollusca / Q000032:analysis*; D009124:Muscle Proteins / Q000032:analysis*; D014335:Tropomyosin / Q000032:analysis; D014336:Troponin / Q000032:analysis*
D000199:Actins; D009124:Muscle Proteins; D014335:Tropomyosin; D014336:Troponin; D000251:Adenosine Triphosphatases; D002118:Calcium