Extramitochondrial localization of glutamate dehydrogenase isozymes in Saccharomyces cerevisiae

The metabolic process of glutamate synthesis in Saccharomyces cerevisiae is governed by a functional model that assumes extramitochondrial localization of glutamate dehydrogenase (GDH). In S. cerevisiae, GDH exists as three isozymes: Gdh1p and Gdh3p, which are NADP-dependent, and Gdh2p, which is NAD-dependent. Previous work has suggested nuclear and/or cytosolic localization, but definitive data are lacking. We attempted to determine the subcellular localization of the three GDH isozymes by enzymatic activity.