The isolation of metallothionein and its protective role in cadmium poisoning

Amino-acid sequence of equine renal metallothionein-1B.

“…The sequence from Pro-3 to Arg-25 was established unambiguously on fragment AP-1I using automated sequence analysis (23 steps (3,5,8,9,15,16,36). In equine tissues the existence of such variants was inferred from the extensive microheterogeneity encountered in all preparations of metallothionein isolated by the standard procedure (4).…”

“…Metallothionein, a cadmium-and zinc-containing, cysteine-rich protein of low molecular weight, was recognized in equine renal cortex by Margoshes and Vallee in 1957 (1, 2). The same protein occurs in large quantity also in human kidney (3), in equine and human liver (4,5), and accumulates in various parenchymatous tissues of laboratory animals after administration of salts of cadmium, zinc, or certain other heavy metals, implicating a role in metal metabolism and detoxication (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Similar proteins have recently also been identified in lower vertebrates (18) and yeast (19).…”

Factors influencing metabolism and toxicity of metals: a consensus report

“…in drinking water and intraperitoneal injections of 1 mg Cd/day). In a subsequent study with dietary exposure, Kimura et al (131) provided evidence in support of the data by Feldman and Cousins (130). Kimura et al (131) found effects only at high oral doses.…”

The chemical form of cadmium in subcellular fractions following cadmium exposure.

“…Gel filtration of extracts of the subcellular par- (6)(7)(8)(9). Furthermore, Waku et al (23) found that metallothionein had no inhibitory effect on the activity of the microsomal enzyme, acyltransferase, whose activity was inhibited by Cd.…”

“…Most of the Cd thus accumulated in the organs is bound to metallothionein located in the cytosol (4,5). Recent studies have shown that the metallothionein may have a protective role against Cd poisoning (6)(7)(8)(9).…”