Bullfrog skeletal myofibril troponin can be completely replaced by rabbit skeletal or bovine cardiac troponin while retaining ATPase activity.
Troponin in bullfrog skeletal myofibrils was found to be replaced completely with either rabbit skeletal or bovine cardiac troponin added to the incubating solution of pH 6.2 at 25C. The myofibrils, in which troponin was replaced with rabbit skeletal troponin, showed almost the same Ca+-or Sr2+-activated ATPase as the intact bullfrog or rabbit skeletal myofibrils. On the other hand, the myofibrils hybridized with bovine cardiac troponin showed the Ca2+-
Shiraishi et al. (1993) studied this question.