|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 204, Issue 6 1053-1061, Copyright © 2001 by Company of Biologists
JOURNAL ARTICLES |
A Sacher, A Cohen and N Nelson
Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Transition metals are essential for many metabolic processes, and their homeostasis is crucial for life. Metal-ion transporters play a major role in maintaining the correct concentrations of the various metal ions in living cells. Little is known about the transport mechanism of metal ions by eukaryotic cells. Some insight has been gained from studies of the mammalian transporter DCT1 and the yeast transporter Smf1p by following the uptake of various metal ions and from electrophysiological experiments using Xenopus laevis oocytes injected with RNA copies (c-RNA) of the genes for these transporters. Both transporters catalyze the proton-dependent uptake of divalent cations accompanied by a 'slippage' phenomenon of different monovalent cations unique to each transporter. Here, we further characterize the transport activity of DCT1 and Smf1p, their substrate specificity and their transport properties. We observed that Zn(2+) is not transported through the membrane of Xenopus laevis oocytes by either transporter, even though it inhibits the transport of the other metal ions and enables protons to 'slip' through the DCT1 transporter. A special construct (Smf1p-s) was made to enhance Smf1p activity in oocytes to enable electrophysiological studies of Smf1p-s-expressing cells. 54Mn(2+) uptake by Smf1p-s was measured at various holding potentials. In the absence of Na(+) and at pH 5.5, metal-ion uptake was not affected by changes in negative holding potentials. Elevating the pH of the medium to 6.5 caused metal-ion uptake to be influenced by the holding potential: ion uptake increased when the potential was lowered. Na(+) inhibited metal-ion uptake in accordance with the elevation of the holding potential. A novel clutch mechanism of ion slippage that operates via continuously variable stoichiometry between the driving-force pathway (H(+)) and the transport pathway (divalent metal ions) is proposed. The possible physiological advantages of proton slippage through DCT1 and of Na(+) slippage through Smf1p are discussed.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  N. C. Andrews Forging a field: the golden age of iron biology Blood, July 15, 2008; 112(2): 219 - 230. [Full Text] [PDF]
|
|
|
|
 |
|
 P. Courville, E. Urbankova, C. Rensing, R. Chaloupka, M. Quick, and M. F. M. Cellier Solute Carrier 11 Cation Symport Requires Distinct Residues in Transmembrane Helices 1 and 6 J. Biol. Chem., April 11, 2008; 283(15): 9651 - 9658. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Sullivan, M. J. Lewis, E. Nikko, and H. R.B. Pelham Multiple Interactions Drive Adaptor-Mediated Recruitment of the Ubiquitin Ligase Rsp5 to Membrane Proteins In Vivo and In Vitro Mol. Biol. Cell, July 1, 2007; 18(7): 2429 - 2440. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Kaler and R. Prasad Molecular cloning and functional characterization of novel zinc transporter rZip10 (Slc39a10) involved in zinc uptake across rat renal brush-border membrane Am J Physiol Renal Physiol, January 1, 2007; 292(1): F217 - F229. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Nevo and N. Nelson The Mutation F227I Increases the Coupling of Metal Ion Transport in DCT1 J. Biol. Chem., December 17, 2004; 279(51): 53056 - 53061. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Kordas and R. J. Stoltzfus New Evidence of Iron and Zinc Interplay at the Enterocyte and Neural Tissues J. Nutr., June 1, 2004; 134(6): 1295 - 1298. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Barisani, A. Parafioriti, M. T. Bardella, H. Zoller, D. Conte, E. Armiraglio, C. Trovato, R. O. Koch, and G. Weiss Adaptive changes of duodenal iron transport proteins in celiac disease Physiol Genomics, May 19, 2004; 17(3): 316 - 325. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Serrano, D. Bernal, E. Simon, and J. Arino Copper and Iron Are the Limiting Factors for Growth of the Yeast Saccharomyces cerevisiae in an Alkaline Environment J. Biol. Chem., May 7, 2004; 279(19): 19698 - 19704. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Cohen, Y. Nevo, and N. Nelson The first external loop of the metal ion transporter DCT1 is involved in metal ion binding and specificity PNAS, September 16, 2003; 100(19): 10694 - 10699. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Forbes and P. Gros Iron, manganese, and cobalt transport by Nramp1 (Slc11a1) and Nramp2 (Slc11a2) expressed at the plasma membrane Blood, September 1, 2003; 102(5): 1884 - 1892. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Arredondo, P. Munoz, C. V. Mura, and M. T. Nunez DMT1, a physiologically relevant apical Cu1+ transporter of intestinal cells Am J Physiol Cell Physiol, June 1, 2003; 284(6): C1525 - C1530. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Reeve, D. Hummel, N. Nelson, and J. Voss Overexpression, purification, and site-directed spin labeling of the Nramp metal transporter from Mycobacterium leprae PNAS, June 25, 2002; 99(13): 8608 - 8613. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. G. Kehres, A. Janakiraman, J. M. Slauch, and M. E. Maguire SitABCD Is the Alkaline Mn2+ Transporter of Salmonella enterica Serovar Typhimurium J. Bacteriol., June 15, 2002; 184(12): 3159 - 3166. [Abstract] [Full Text] [PDF]
|
|
