The oxoglutarate/malate carrier of rat brain mitochondria operates by a uniport exchange mechanism.

Here, the oxoglutarate carrier, already isolated from various sources and described in the literature, has been purified from rat brain and reconstituted in proteoliposomes for an accurate kinetic study. The rate of uptake of labelled oxoglutarate and malate has been measured in various conditions, essentially in double substrate experiments. The data so obtained fit the hypothesis that the carrier operates by a uniport-exchange mechanism and provide significant values for the kinetic constants and the equilibrium constants implied in the process. Their analysis leads to the conclusion that the carrier is maximally efficient in the exchange between external malate and internal oxoglutarate, as required by the malate/aspartate shuttle, which should be the main role of the oxoglutarate carrier in brain mitochondria.