Interaction of adenine nucleotides with the adenine nucleotide translocase regulates the developmental changes in proton conductance of the inner mitochondrial membrane.

2-h-old neonatal liver mitochondria, when depleted of adenine nucleotides, showed an 'ohmic' current-voltage relationship and a higher passive proton permeability of the membrane, resembling fetal mitochondrial behaviors for the proton conductance. Incubation of fetal mitochondria with ATP, GDP or carboxyatractyloside promoted a significant reduction in the passive proton permeability of the membrane and the appearance of the characteristic biphasic behavior for the proton conductance. It is concluded that the postnatal increase in intramitochondrial adenine nucleotide concentration promotes, by the interaction of the nucleotides with the adenine nucleotide translocase, the reduction in the passive proton permeability of the mitochondrial membrane, allowing efficient energy conservation in the neonatal liver.