Simultaneous induction of Pb-metallothionein-like protein and Zn-thionein in the liver of rats given lead acetate.
Administration of a sublethal dose of lead acetate to rats induced the simultaneous synthesis of a Pb-metallothionein (Pb-MT)-like protein (Pb-BP) and Zn-thionein (Zn-BP) in the liver. The Pb-BP had an apparent molecule mass of 6900 Da and seemed to bind preferentially to lead in the liver cytosol. The Zn-BP was identified by comparison of the Mr, elution profiles from Sephadex G-75 and DEAE-Sephadex A-25 columns, and polyacrylamide-gel-electrophoretic mobility, with those of rat liver Zn-MT-II. The Pb-BP accumulated in the liver to a maximum 6 h after the intraperitoneal injection of lead acetate and accounted for about 60% of the lead in the liver cytosol at this stage. However, after that, it gradually decreased in the liver, until it was close to the basal amount 24 h after the induction. In contrast, the amount of Zn-MT increased gradually, reached a maximum 12 h after the administration of lead acetate and maintained a constant value until at least 24 h after the induction. Amino acid analysis of the Pb-BP indicated that it contained about 28% half-cysteine. These results strongly suggest that lead acetate induces the synthesis of Pb-MT as well as Zn-MT in rat liver.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002850:Chromatography, Gel; D003609:Dactinomycin / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D007854:Lead / Q000378:metabolism / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D046911:Macromolecular Substances; D008297:Male; D008668:Metallothionein / Q000378:metabolism*; D009942:Organometallic Compounds; D051381:Rats; D011919:Rats, Inbred Strains
D000596:Amino Acids; D046911:Macromolecular Substances; D009942:Organometallic Compounds; C048226:lead metallothionein; C021267:zinc thionein; D003609:Dactinomycin; D007854:Lead; D008668:Metallothionein; C008261:lead acetate