Energy-linked functions of tightly coupled mitochondria isolated from Ehrlich ascites tumor cells.

Tightly coupled mitochondria isolated from Ehrlich ascites tumor cells contain a latent adenosine triphosphatase (ATPase) that is stimulated by a range of dinitrophenol concentrations up to 0.5 mM. Maximal uncoupler-stimulated ATPase activity is approximately 60% of that found with rat liver mitochondria and is inhibited by oligomycin and by atractyloside. Rapid rates of ATPase activity accompany the accumu lation of Ca2+ by ascites tumor mitochondria in an adeno sine triphosphate-supported system. In contrast to Ca2+, Mg2+ is unable to induce ATPase activity in intact mito