Rapid induction of copper-binding proteins in the gills of metal exposed mussels

Abstract

The exposure of the mussel Mytilus galloprovincialis Lam. to sublethal concentrations of Cu 2+ (0.08 ppm) for 24–48 hr results in the appearance of low molecular weight (about 12,000), heat stable copper-binding proteins in the soluble extracts obtained from the gills. 2. The soluble low molecular weight copper-binding proteins do not occur in the gill extracts from the controls and from the mussels submitted to a short intoxication (4 hr). 3. The incorporation of 35S cysteine into the 12,000 molecular weight copper-rich fraction from the gills of mussels exposed for 48 hr to Cu 2+ is 7–10 fold greater than in controls. This result strongly supports the inducible nature of these proteins. 4. The low molecular weight proteins synthesized in response to the uptake of Cu 2+ show many of the characteristics of metallothioneins, having a high SH content, few aromatic amino acids and a high metal binding capacity.