Beef liver glutamate dehydrogenase was 3hown to bind specifically to the ‘inside—out” vesicles (sub mitochondrial particles) prepared from beef liver mitochondria. Binding was shown to increase with decreasing ionic strength and pH. Some metabolites which are known to interact with the enzyme and bring about changes in its conformation also affected binding. It is suggest d that in mitochondria, the enzyme may partition between the membrane and the mitochondrial matrix in a manner responsive to local variations in ionic strength and metabolite concentrations. As cardiolipin is present in the inner mitochondrial membrane and interacts with the enzyme with loss of its catalytic activity (1-4), these results may have important physiological significance for the activity of the enzyme “in vivo”.