ATP dependent uptake of zinc by human erythrocyte ghosts.

The energy dependence of Zn2+ accumulation by human erythrocytes was studied by preparing resealed ghosts loaded with ATP or AMP. Uptake of Zn2+ was followed by radioactivity or atomic absorption spectroscopy measurements. Zn2+ taken up is not adsorbed by the membrane but transported into the ghosts. Ghosts containing ATP took up more Zn2+ than those containing AMP. The effect is not specific for ATP, however, GTP and CTP showing the same increased uptake. Zn2+ uptake by ATP ghosts can be further drastically enhanced by addition of Cu2+. Therefore, in spite of the enhancement of Zn2+ uptake by ATP, Zn2+ seems to be accumulated by a passive mechanism even when the ghosts contain ATP. The accumulation is probably brought about by binding of Zn2+ to substances inside the ghosts.