AJP - Cell Physiology, Vol 269, Issue 4 C892-C898, Copyright © 1995 by American Physiological Society

ARTICLES

Copper transport and kinetics in cultured C6 rat glioma cells

Y. Qian, E. Tiffany-Castiglioni and E. D. Harris
Department of Biochemistry, Texas A&M University, College Station 77843, USA.

C6 rat glioma cells accumulate and efflux 67Cu. Both processes showed saturation kinetics with increasing 67Cu concentration. The Michaelis constant (Km) for uptake was 0.63 +/- 0.14 microM; maximum velocity (Vmax) was 3.29 +/- 0.57 pmol Cu.mg protein-1.min-1. The Km for efflux was 0.15 +/- 0.06 microM; Vmax was 1.08 +/- 0.71 pmol Cu.mg protein-1.min-1. p-Chloromercuribenzoate (p-CMB) totally blocked 67Cu efflux but had no effect on Km or Vmax of uptake. Total 67Cu in the cell after 50 min was partitioned equally between particulate and soluble fractions. p-CMB-treated cells accumulated more 67Cu, but < 10% was bound to the particulate (membrane) fraction. Pb also increased 67Cu accumulation without affecting Km and Vmax of 67Cu uptake. These data suggest that carriers for import and export of Cu in C6 cells are distinct or operate in two different cellular environments. Efflux is a sulfhydryl-dependent process subject to inhibition by Pb. The data are consistent with a P-type ATPase in the efflux of Cu from cells and the potential for Pb to inhibit the efflux mechanism.

This article has been cited by other articles:

				J. Lee, M. M. O. Pena, Y. Nose, and D. J. Thiele Biochemical Characterization of the Human Copper Transporter Ctr1 J. Biol. Chem., February 1, 2002; 277(6): 4380 - 4387. [Abstract] [Full Text] [PDF]

				D. D. McAbee and X. Jiang Copper and Zinc Ions Differentially Block Asialoglycoprotein Receptor-mediated Endocytosis in Isolated Rat Hepatocytes J. Biol. Chem., May 21, 1999; 274(21): 14750 - 14758. [Abstract] [Full Text] [PDF]