title: Rapid kinetics of calcium ion transport and ATPase activity in the sarcoplasmic reticulum of dystrophic muscle.
abstract: Vesicular fragments of sarcoplasmic reticulum were isolated from pectoralis muscle of normal and dystrophic chicken. Purification of both preparations was equally satisfactory, as shown by a prominent ATPase band in electrophoresis gels. Measurements of ATPase phosphorylation, Ca2+ transport and Pi cleavage by rapid quench methods revealed a lower specific activity of the dystrophic vesicles with respect to all of these functions. On the other hand, Ca2+-independent ATPase activity was found to be increased in dystrophic vesicles. It is suggested that a fraction of ATPase units of dystrophic sarcoplasmic reticulum is not activated by Ca2+, owing to an altered protein assembly within the membrane bilayer. In fact, when the membrane structure is perturbed by detergents normal and dystropic preparations acquire an equally high Ca2+-dependent ATPase.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002645:Chickens; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009132:Muscles / Q000378:metabolism*; D009137:Muscular Dystrophy, Animal / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
chemical_list: D000251:Adenosine Triphosphatases; D008274:Magnesium; D002118:Calcium