Differential effects of -amanitin on RNA polymerase activity in nuclei and mitochondria.

Abstract

Concentrations of α-amanitin which strongly inhibit nuclear RNA polymerase activity in presence of Mn2+ and ammonium sulfate did not produce any significant inhibition of RNA polymerase activity in mitochondria from rat brain, spleen, liver, and kidney under identical conditions. Much higher concentrations of α-amanitin, however, inhibited the mitochondrial RNA polymerase. The effects of α-amanitin on the mitochondrial RNA polymerase activity in presence of Mg2+ were similar to those on nuclear enzyme under the same conditions; in both cases only relatively very high concentrations produced significant inhibition.