ATP-driven copper transport across the intestinal brush border membrane
Martin Knöpfel1, Craig Smith, Marc Solioz
1Department of Clinical Pharmacology, University of Berne, 3010 Berne, Switzerland. tracechem@tiscali.ch
Biochemical and Biophysical Research Communications
|April 6, 2005
Summary
Belgrade rats with a DMT1 mutation show disrupted copper transport. However, an ATP-driven system in intestinal membranes facilitates high-affinity copper uptake, suggesting a primary route for absorption.
Area of Science:
- Biochemistry
- Molecular Biology
- Gastroenterology
Background:
- Divalent metal ion transporter 1 (DMT1) is crucial for metal ion absorption in the small intestine.
- Belgrade rats possess a mutation (G185R) in DMT1, impacting its transport function.
- DMT1 transports various divalent metal ions, including copper (Cu2+).
Purpose of the Study:
- To investigate the role of DMT1 and other systems in copper transport across the intestinal brush border membrane.
- To characterize copper uptake mechanisms in Belgrade rats with a functional or non-functional DMT1.
Main Methods:
- Utilized brush border membrane (BBM) vesicles from Belgrade rats (b/b and +/b genotypes).
- Employed calcein fluorescence quenching assay to measure copper transport.
- Assessed copper transport in both unenergized and ATP/magnesium-energized BBM vesicles.
Main Results:
- Copper transport was impaired in unenergized BBM vesicles of b/b Belgrade rats, similar to iron transport.
- +/b Belgrade rat vesicles showed normal copper transport, indicating DMT1's role.
- Both b/b and +/b vesicles exhibited similar high-affinity copper accumulation when energized with ATP and magnesium.
Conclusions:
- Intestinal brush border membranes possess an ATP-driven, high-affinity copper transport system.
- This ATP-dependent system may represent the primary pathway for intestinal copper uptake, independent of DMT1 function.
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