Glutamate biosynthesis superpathway (Saccharomyces cerevisiae)

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The utilization of ammonia to synthesize glutamate occurs through two pathways in most microorganisms. In the first pathway, glutamate is synthesized through the reductive amination of -ketoglutarate by glutamate dehydrogenase. Two NADPH-dependent glutamate dehydrogenases exist in S. cerevisiae: Gdh1p and Gdh3p. GDH1 is highly expressed when either ethanol or glucose is used as the carbon source, whereas GDH3 is glucose-repressed and induced only in ethanol. The second route of glutamate biosynthesis involves the combined action of glutamine synthetase (Gln1p) and glutamate synthase (Glt1p). In the first step, glutamate reacts with a molecule of ammonia in a reaction catalyzed by Gln1p to form glutamine. In the second, glutamine reacts with -ketoglutarate via Glt1p to form two molecules of glutamate, resulting in a net gain of one for each glutamate molecule that enters the pathway. Source: https://pathway.yeastgenome.org/

GenMAPP remarks 

Based on http://pathway.yeastgenome.org/biocyc/