A zinc enzyme, specific for NADPH. Catalyses the one-electron reduction of certain quinones, with the orthoquinones 1,2-naphthoquinone and 9,10-phenanthrenequinone being the best substrates . Dicoumarol [cf. EC 1.6.5.2 NAD(P)H dehydrogenase (quinone)] and nitrofurantoin are competitive inhibitors with respect to the quinone substrate. The semiquinone free-radical product may be non-enzymically reduced to the hydroquinone or oxidized back to quinone in the presence of O2 . In some mammals, the enzyme is abundant in the lens of the eye, where it is identified with the protein zeta-crystallin.
The taxonomic range for the selected organisms is: Saccharomyces cerevisiae The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
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SYSTEMATIC NAME
IUBMB Comments
NADPH:quinone oxidoreductase
A zinc enzyme, specific for NADPH. Catalyses the one-electron reduction of certain quinones, with the orthoquinones 1,2-naphthoquinone and 9,10-phenanthrenequinone being the best substrates [1]. Dicoumarol [cf. EC 1.6.5.2 NAD(P)H dehydrogenase (quinone)] and nitrofurantoin are competitive inhibitors with respect to the quinone substrate. The semiquinone free-radical product may be non-enzymically reduced to the hydroquinone or oxidized back to quinone in the presence of O2 [1]. In some mammals, the enzyme is abundant in the lens of the eye, where it is identified with the protein zeta-crystallin.
the human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding proteins and that this property has been conserved in zeta-crystallins throughout evolution. This supports a role for zeta-crystallins as trans-acting factors that could regulate the turnover of certain mRNAs
the human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding proteins and that this property has been conserved in zeta-crystallins throughout evolution. This supports a role for zeta-crystallins as trans-acting factors that could regulate the turnover of certain mRNAs
interference of NADPH on Zta1p binding to RNA is much lower than that of NADPH on human zeta-crystallin, consistent with a weaker binding of NADPH to the yeast enzyme
yeast zeta-crystallin is a quinone oxidoreductase belonging to the zeta-crystallin family, with activity in the reduction of alkenal/alkenone compounds. The lack of Zta1 negatively affects the expression of a group of genes involved in amino acid biosynthesis. Zta1 participates in the post-transcriptional regulation of ARG4 expression by increasing the ARG4 mRNA half-life. Expression of the zeta-crystallin gene is itself regulated by nutrient availability through the general amino acid control and target of rapamycin pathways
The yeast zeta-crystallin/NADPH quinone oxidoreductase (Zta1p) is under nutritional control by the target of rapamycin pathway and is involved in the regulation of argininosuccinate lyase mRNA half-life