Inhibition of malate transport and activation of phosphate transport in mitochondria by ethylmercurithiosalicylate

Abstract

Different phosphate-transport systems have been described in mitochondria [ 11. Since so far no phosphate carrier protein could be isolated, the identification of phosphate-transport systems rely only on indirect studies using SH-inhibitors. The reactivity of SH-inhibitors, however, depends strongly on the conditions applied [2]. The phosphate/proton-symporter of mitochondria is sensitive against SH-inhibitors like mersalyl or MalNEt [ 1,3]. The effect of thiomersal on phosphate transport in rat liver mitochondria has been studied [4]. The MalNEtor PMS-inhibited phosphate transport could be reactivated by thiomersal. Here we show that the activation of phosphate transport by thiomersal paralleles an inhibition of malate transport. The data suggest that in the presence of thiomersal the phosphate/dicarboxylate antiporter behaves like a phosphate/proton symporter.