Activation of delta-aminolevulinic acid dehydratase following donation of zinc from kidney metallothionein.
Metallothionein has been postulated to function in essential metal homeostasis. In this study, we demonstrate a 1.7-fold increase in purified bovine liver delta-aminolevulinic acid dehydratase (ALAD) activity following incubation with purified kidney Zn-thionein isolated from Zn-treated rats. The mechanism of enzyme activation, as demonstrated using 65Zn-labeled thionein, involves direct transfer of Zn from Zn-thionein to ALAD. These data support the hypothesis that metallothionein serves to regulate the intracellular bioavailability of essential cations, functioning as a reservoir or conduit through which metals are donated to enzymes which require them as cofactors.
D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D004789:Enzyme Activation / Q000187:drug effects; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D008668:Metallothionein / Q000378:metabolism*; D000623:Porphobilinogen Synthase / Q000378:metabolism*; D051381:Rats; D015032:Zinc / Q000378:metabolism* / Q000494:pharmacology
C021267:zinc thionein; D008668:Metallothionein; D000623:Porphobilinogen Synthase; D015032:Zinc