The atp-dependent copper transporter, in the golgi apparatus of rat
hepatocytes, transports cu(ii) not cu(i).
Bingham, M J, T J Ong, W J Ingledew, and H J McArdle.
Department of Child Health, Ninewells Hospital and Medical School,
University of Dundee, Dundee, DD1 9 SY. UK, Department of
Biochemistry, University of St Andrews, St Andrews, Fife KY16 9JF,
UK
APStracts 3:0097G, 1996.
The Wilson disease ATPase (ATP7B) is believed to bind Cu as Cu(I). We
provide evidence to suggest that the ATPase actually transports Cu as
Cu(II). When the Cu is presented to rat liver microsomes as Cu(I),
virtually all uptake is ATP independent. If the Cu is presented as
Cu-oxalate (Cu(II)), total uptake is reduced to about 10 % of Cu(I)
levels, but ATP dependent uptake rises, both as a proportion of total
uptake and in absolute terms. The reducing agent vitamin C and the
Cu(I) chelator bathocuproine both over ride the effect of oxalate.
The data indicate that there are two transporters in microsomes, an
ATP independent Cu(I) transporter and an ATP dependent Cu(II) pump.
The activity of the Cu(I) transporter correlates most strongly with
alkaline phosphatase, suggesting that it derives from plasma membrane
contamination. Cu(II) ATP dependent transport correlates only with
[beta]1,4 galactosyltransferase which indicates that it is located in
the Golgi apparatus.
Received 20 February 1996; accepted in final form 11 April 1996.
APS Manuscript Number G68-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96