The human 32‐kDa stress protein induced by exposure to arsenite and cadmium ions is heme oxygenase

Exposure of HeLa and HL60 cells to sodium arsenite or cadmium chloride led to marked increases in cellular heme oxygenase activity. SDS-polyacrylamide gel electrophoresis of [35S]methionine-labeled cellular proteins indicated that these treatments also resulted in the induction of a 32-kDa protein. Immunoblot analysis further showed that the 32-kDa protein reacted with anti-bovine heme oxygenase antibodies. Treatment of the cells with cobaltic chloride or heat induced neither the 32-kDa protein nor heme oxygenase activity. It is concluded that the 32-kDa stress protein induced by arsenite and cadmium ions in these human cells is heme oxygenase.