(31) INTERACTION BETWEEN THE ADP/ATP TRANSLOCASE AND THE CA-ACTIVATED NON-SPECIFIC CHANNEL OF THE MITOCHONDRIAL INNER MEMBRANE: WHAT THE REVEWERS DIDN'T WANT YOU TO SEE

Robert A. Haworth and Douglas R. Hunter
Department of Surgery, University of Wisconsin, Madison, WI 53792, USA

Publication of our series of papers "The Ca-induced transition in Mitochondria" (Arch. Biochem. Biophys. 195:453-477 (1979)) and "Allosteric inhibition of the Ca-activated hydrophilic channel of the mitochondrial inner membrane by nucleotides" (J. Membrane Biol. 54:231-236 (1980)) was difficult, as the concept of a Ca-induced transition was met with a great deal of skepticism. The following paragraph is the abstract of a paper, which we will present, which was originally submitted to Biochim. Biophys. Acta in 1980, but which was never published: ADP binding at the ADP/ATP translocase causes inhibition of the Ca-induced permeability of the mitochondrial inner membrane. Inhibition is prevented by carboxyatractyloside, but potentiated by bongkrekic acid. It requires the addition of ADP before Ca, and the inhibition decays with a half time of about 45 sec. It is as though ADP binding delays Ca binding to the channel which controls non-specific permeability. Inhibition cannot, however, be relieved by A23187. This direct effect of ADP binding suggests that the ADP/ATP translocase physically interacts with the Ca-specific channel which controls the non-specific permeability of the mitochondrial inner membrane.