ATP-driven copper transport across the intestinal brush border membrane.
The divalent metal ion transporter DMT1 is localized in the brush border membrane (BBM) of the upper small intestine and has been shown to be able to transport Mn2+, Fe2+, Co2+, Ni2+, and Cu2+. Belgrade rats have a glycine-to-arginine (G185R) mutation in DMT1, which affects its function. We investigated copper transport with BBM vesicles of Belgrade rats loaded with calcein, which exhibits fluorescence quenching by various metal ions. Transport of copper was disrupted in unenergized BBM vesicle of b/b Belgrade rats, as had been described for iron transport, while +/b vesicles exhibited normal transport by DMT1. When either b/b or +/b vesicles were loaded with ATP and magnesium, similar high-affinity accumulation of copper was observed in both types of vesicles. Thus, brush border membranes possess an ATP-driven, high-affinity copper transport system which could serve as the primary route for copper uptake by the intestine.
Knöpfel
Martin
M
Department of Clinical Pharmacology, University of Berne, 3010 Berne, Switzerland. tracechem@tiscali.ch
Smith
Craig
C
Solioz
Marc
M
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D002413:Cations, Divalent / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D003035:Cobalt / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D017136:Ion Transport / Q000187:drug effects; D033862:Iron-Binding Proteins / Q000235:genetics / Q000378:metabolism; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009532:Nickel / Q000378:metabolism; D051381:Rats; D013050:Spectrometry, Fluorescence; D000099236:Solute Carrier Family 11, Member 2
D000255:Adenosine Triphosphate; D027682:Cation Transport Proteins; D002413:Cations, Divalent; D003035:Cobalt; D003300:Copper; D033862:Iron-Binding Proteins; D009532:Nickel; D000099236:Solute Carrier Family 11, Member 2