Biological significance of non-acetylated metallothionein.
The biological significance of non-acetylated metallothionein (MT) was investigated from the viewpoint of N(alpha)-acetylation after induction of MT synthesis by metallic and non-metallic inducers, by partial hepatectomy and under physiological conditions. N(alpha)-Acetylated and non-acetylated forms of MT-2 in liver supernatants and plasma were detected by the tandem size-exclusion and anion-exchange HPLC columns with in-line detection by mass spectrometry. The non-acetylated isoform of MT-2 (MT-2') was present at a comparable level to the N(alpha)-acetylated form of MT-2 (MT-2) at an early stage after induction by not only zinc but also cadmium, and by partial hepatectomy in the livers of rats. Plasma MT-2 in neonatal rats was similar to liver MT-2 in the composition of N(alpha)-acetylated and non-acetylated forms, suggesting that there are no differences in the roles of N(alpha)-acetylation of MT in the extracellular trafficking of MT. The column switching HPLC method with in-line detection by inductively coupled argon plasma mass spectrometry (ICP-MS) was shown to be a sensitive and powerful method to detect MT proteins at not only isoform level but also at acetylated and non-acetylated form levels.
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Faculty of Pharmaceutical Sciences, Chiba University, Inage, Japan.
Suzuki
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D000107:Acetylation; D000818:Animals; D000831:Animals, Newborn / Q000097:blood / Q000378:metabolism; D002104:Cadmium / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005110:Extracellular Space / Q000378:metabolism; D006498:Hepatectomy; D006586:Hexanes / Q000494:pharmacology; D008099:Liver / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008668:Metallothionein / Q000032:analysis* / Q000096:biosynthesis / Q000097:blood*; D051381:Rats; D017208:Rats, Wistar; D015032:Zinc / Q000494:pharmacology
D006586:Hexanes; D002104:Cadmium; C026385:n-hexane; D008668:Metallothionein; D015032:Zinc