Low Molecular Weight Copper-Binding Proteins in Cultured Human Cells

Abstract

Not a great deal is known of the molecular mechanisms whereby heavy metals are handled intracellularly. The elucidation of these mechanisms which may be defective in certain genetic diseases or stressed in some environmental situations is essential to the understanding of both the overall homeostasis and toxicology of heavy metals. Studies of either of these aspects in humans are limited to the analysis of the readily available body fluids or pathological specimens which may be available on occasion. The use of human cells in long term culture avoids these limitations. This report describes the uptake of ⁶⁷Cu²⁺ by cultured fibroblasts and lymphoblasts and the subcellular distribution of Cu²⁺ in these cells. A significant portion of the Cu²⁺ is associated with a soluble protein fraction of similar size to that observed in tissues, particularly liver and kidney of humans as well as animals (1–17). Hence, the induction and biosynthesis of, as well as possible genetic variations among these proteins, become susceptible to investigations in human cells.