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Fig. 2. Energy export from mitochondria matrix and intracristal space. Restricted
diffusion of nucleotides from the narrow intracristal space to the external
compartment could be overcome by an enzymatic system and/or by high-throughput
contact sites traversing the inner (im) and outer (om) membranes. In some
circumstances, contact sites could provide direct access to ATP in the matrix
compartment, while intracristal space could be used for proton confinement
leading to efficient ATP synthesis. E, E1, E2,
near-equilibrium phosphotransfer enzymes; ANT, adenine nucleotide
translocator.