Abstract
Glutamate dehydrogenase (GDH) of animal cells is usually considered to be a mitochondrial enzyme. However, this enzyme has recently been reported to be also present in nucleus, endoplasmic reticulum and lysosomes. These extramitochondrial localizations are associated with moonlighting functions of GDH, which include acting as a serine protease or an ATP-dependent tubulin-binding protein. Here, we review the published data on kinetics and localization of multiple forms of animal GDH taking into account the splice variants, post-translational modifications and GDH isoenzymes, found in humans and apes. The kinetic properties of human GLUD1 and GLUD2 isoenzymes are shown to be similar to those published for GDH1 and GDH2 from bovine brain. Increased functional diversity and specific regulation of GDH isoforms due to alternative splicing and post-translational modifications are also considered. In particular, these structural differences may affect the well-known regulation of GDH by nucleotides which is related to recent identification of thiamine derivatives as novel GDH modulators. The thiamine-dependent regulation of GDH is in good agreement with the fact that the non-coenzyme forms of thiamine, i.e., thiamine triphosphate and its adenylated form are generated in response to amino acid and carbon starvation.
Highlights
IntroductionGlutamate dehydrogenase (EC 1.4.1.3; L-glutamate: NAD(P)+ oxidoreductase, deaminating) catalyzes oxidative deamination of glutamate in a bisubstrate NAD(P)+ -dependent reaction, releasing
Glutamate dehydrogenase (EC 1.4.1.3; L-glutamate: NAD(P)+ oxidoreductase, deaminating) catalyzes oxidative deamination of glutamate in a bisubstrate NAD(P)+ -dependent reaction, releasing2-oxoglutarate, NH3 and NAD(P)H [1,2,3,4,5]
+-dependent ADP-ribosylation of Glutamate dehydrogenase (GDH) is catalyzed by sirtuin 4 (SIRT4)
Summary
Glutamate dehydrogenase (EC 1.4.1.3; L-glutamate: NAD(P)+ oxidoreductase, deaminating) catalyzes oxidative deamination of glutamate in a bisubstrate NAD(P)+ -dependent reaction, releasing. In contrast to animals, plants are thought to mostly assimilation [19] This activity of plant GDH is elevated at increased concentrations of employ the glutamate dehydrogenase trisubstrate (backward) reaction for nitrogen assimilation [19]. Plants use in the bisubstrate enzymes catalyzing the glutamine: 2-oxoglutarate amidotransferase reaction using ferredoxin or reaction. Under these conditions, nitrogen assimilation is performed by the two enzymes catalyzing. In some algae the GDH-dependent production is thought to ferredoxin be the dominant pathway of nitrogen the glutamine: 2-oxoglutarate glutamate amidotransferase reaction using or NADH as electron donors assimilation under normal conditions [22]. Intracellular Localization of GDH in Animals conditions [22]
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