The recognition of two specific binding sites of the adenine nucleotide translocase by palmitoyl CoA in bovine heart mitochondria and submitochondrial particles

Abstract

Palmitoyl CoA which is an effective inhibitor of adenine nucleotide transport is able to remove bound [ 14C]ADP and [ 3H]atractylate from the translocator on the outer side of the inner mitochondrial membrane. Bongkrekic acid, when added to the incubation medium prior to palmitoyl CoA, can prevent the removal of bound [ 14C]ADP from the membrane by palmitoyl CoA, however, bongkrekic acid is ineffective if palmitoyl CoA is added first. Upon incubation with inverted submitochondrial particles, both palmitoyl CoA and bongkrekic acid prevent the uptake and transport of [ 14C]ADP by the particles. Moreover, when the submitochondrial particles are preincubated with [ 14C]ADP, palmitoyl CoA, like bongkrekic acid, is unable to remove the bound nucleotide from the inner face of the carrier. Thus, palmitoyl CoA which has a high affinity for the translocator on both sides of the inner mitochondrial membrane, nevertheless, interacts differently with the carrier on each side of the membrane. This suggests that the translocase contains binding sites in two specific states both of which accommodate palmitoyl CoA.