Mitochondrial glutamate dehydrogenase 1 (GLUD1) catalyzes the reversible reaction of glutamate and NAD(P)+ to form 2-oxoglutarate, NAD(P)H + H+, and ammonia (Fang et al. 2002). Mature GLUD1 protein lacks the 53 aminoterminal residues of the nascent protein (Julliard and Smith 1979), which function as a mitochondrial import signal. The active form of the enzyme is a hexamer, allosterically activated by ADP and inhibited by GTP (Fang et al. 2002; Smith et al. 2002).