REPLACEMENT OF 3 TROPONIN COMPONENTS WITH CARDIAC TROPONIN COMPONENTS WITHIN SINGLE GLYCERINATED SKELETAL-MUSCLE FIBERS

The tension of single glycerinated rabbit skeletal muscle fiber was desensitized to a Ca2+-concentration after treatment with an excessive amount of bovine cardiac troponin T and reached a level of about 70% of the maximum tension of the untreated fiber. A SDS-gel electrophoretic examination indicated that troponin C·I·T complex in the fiber was replaced with the added cardiac troponin T. The Ca2+-sensitivity of the tension of the troponin T-treated fiber was then recovered by the addition of bovine cardiac troponins I and C. The rabbit skeletal muscle fiber thus hybridized with bovine cardiac troponin C·I·T showed the same cooperativity of Ca2+-activation as the cardiac muscle. © 1991.