Glutamate dehydrogenase localization

Aoki C, Milner TA, Berger SB, Sheu K-FR, Blass JP, Pickel VM (1987a) Glial glutamate dehydrogenase ultrastructural localization and regional distribution in relation to the mitochondrial enzyme, cytochrome oxidase. 

Madl JE, Clements JR, Beitz AJ, Wenthold RJ, Larson AA (1988) Immunocytochemical localization of glutamate dehydrogenase in mitochondria of the cerebellum and ultrastructural study using a monoclonal antibody. Brain Res 452 396-402. 

Rothe F, Brosz M, Storm-Mathisen J (1994) Quantitative ultrastructural localization of glutamate dehydrogenase in the rat cerebellar cortex. Neuroscience 62 1133-1146. 

Reactions of the urea cycle occur in both the mitochondria and cytosol of liver cells. Glutamate dehydrogenase, the citric acid cycle enzymes, carbamoyl phosphate synthetase I, and ornithine transcarbamoylase are localized in the mitochondrion, whereas the rest of the cycle occurs in the cytosol. This means that ornithine must be transported into mitochondria, and citrulline must be exported to the cytosol, in order for the cycle to proceed. 

An understanding of the molecular basis for regulation of isocitrate dehydrogenase by phosphorylation was facilitated by X-ray crystallography of the phosphorylated enzyme in complex with isocitrate. The crystal structures of mutants of the enzyme in which SerllS had been exchanged for aspartate or glutamate were also solved (Hurley et al., 1990). The structure of the enzyme in complex with the substrate isocitrate revealed the phophorylation site to be localized near isocitrate. SerllS itself binds the substrate directly via a H-bond with the O of isocitrate (fig. 2.13). 

---