Freedman J H, Peisach J
Institute for Structural and Functional Studies, University City Science Center, Philadelphia, Pennsylvania 19140.
Biochem Biophys Res Commun. 1989 Oct 16;164(1):134-40. doi: 10.1016/0006-291x(89)91693-8.
The distribution of copper in lysates prepared anaerobically from copper-resistant hepatoma cells radiolabeled with 67Cu was examined in pulse-chase experiments. Initially, the majority of the radioactivity (greater than 85%) coeluted with copper-metallothionein. As the chase time increased there was a gradual loss of 67Cu from metallothionein, with a concomitant increase in the level of 67Cu-labeled glutathione. There was also an increase in 67Cu incorporation into superoxide dismutase. These results suggest that the chelation of copper by metallothionein from a copper-glutathione complex (Freedman, J. H., Ciriolo, M. R., and Peisach, J. (1989) J. Biol. Chem. 264, 5598-5605) is a reversible process. Further, they demonstrate that the copper bound to metallothionein is not permanently sequestered, but can be incorporated into other copper proteins.
