Studies on the transition of the cristal membrane from the orthodox to the aggregated configuration. III. Loss of coupling ability of adrenal cortex mitochondria in the orthodox configuration

Abstract

When the cristae of adrenal cortex mitochondria are stabilized in the orthodox configuration by the binding of 20–25 mμmoles/mg protein of either Ca²⁺ or free fatty acids (oleic acid), both the capacity for carrying out coupled reactions and the capacity for undergoing energized configurational transitions are lost. The coupled reactions studied included ATP synthesis, divalent cation translocation, monovalent cation trnaslocation, and reversed electron transfer. The coupled processes and energized configurational changes are fully operative when the cristae of adrenal cortex mitochondria are in the aggregated configuration. However, two processes that have been shown to depend on conformational changes (the anaerobic-aerobic proton ejection and energized accumulation of inorganic phosphate) still proceed when mitochondria are in the orthodox configuration. When the mitochondria are initially in the orthodox configuration, addition of divalent cations (Mg²⁺ or Mn²⁺) or albumin induces a transition of the cristae to the aggregated configuration and leads to restoration of all the coupled processes. the orthodox to aggregated transition is reversible and the modulation of this reversibility appears to be one of the key points of control in the mitochondrion and possibly of cellular functions.