Coenzyme A enhances activity of the mitochondrial adenine nucleotide translocator

The adenine nucleotide translocator (ANT) accomplishes the exchange of ATP from the mitochondrial matrix with cytoplasmic ADP. While investigating the biochemical mechanism of retinoic acid (RA) on the ANT via retinoylation, we have found and subsequently demonstrated a positive influence of Coenzyme A (CoA) on the transport of ATP across the membranes of rat liver mitochondria. CoA enhances ANT activity in a dose-dependent manner modifying the Vmax (673.3 ± 20.7 nmol ATP/mg protein/min versus 155.0 ± 1.9 nmol ATP/mg protein/min), the IC50 for the specific inhibitor carboxyatractyloside (CATR) (0.142 ± 0.012 μM versus 0.198 ± 0.011 μM) but not the Km (22.50 ± 0.52 μM versus 22.19 ± 0.98 μM). Data suggest a likely enzymatic involvement in the interaction between ANT and CoA. The effect of CoA is observed in mitochondria from several different tissues.