Copper uptake and intracellular distribution in the human intestinal Caco-2 cell line

The apical uptake of (CuCl2)-Cu-64 was investigated in human differentiated intestinal Caco-2 cells grown on permeable supports. At pH 6.0 in the apic al compartment, the uptake of copper was linear over the first 6 min and be tween 10 and 80 mu M CuCl2 exhibited non-saturable transport kinetics. In a ddition, copper uptake was energy-independent, affected by the valency stat e of copper, preferring Cu(II) over Cu(I), and not influenced by high (10 m M) extracellular calcium. The intracellular distribution of copper was inve stigated by FPLC at different times of uptake ('pulse') and of 'chase'. Int racellular copper initially bound predominantly to low molecular weight com ponents (i.e., glutathione), and subsequently shifted to higher molecular w eight components such as metallothionein and Cu,Zn superoxide dismutase.