The N-terminus of the human copper transporter 1 (hCTR1) is localized extracellularly, and interacts with itself.
We have used indirect immunofluorescense studies and glycosylation-site insertion and deletion mapping to characterize the topology of human copper transporter 1 (hCTR1), the putative human high-affinity copper-import protein. Both approaches indicated that hCTR1 contains three transmembrane domains and that the N-terminus of hCTR1, which contains several putative copper-binding sites, is ... localized extracellularly, whereas the C-terminus is exposed to the cytosol. Based on previous observations that CTR1 proteins form high-molecular-mass complexes, we investigated directly whether CTR1 proteins interact with themselves. Yeast two-hybrid studies showed that interaction of yeast, mouse, rat and human CTR1 occurs at the sites of their N-terminal domains, and is not dependent on the copper concentration in the growth media. Analysis of deletion constructs indicated that multiple regions in the N-terminus are essential for this self-interaction. In contrast, the N-terminal tail of the presumed low-affinity copper transporter, hCTR2, does not interact with itself. Taken together, these results suggest that CTR1 spans the membrane at least six times, permitting formation of a channel, which is consistent with its proposed role as a copper transporter.
Mesh Terms:
Amino Acid Sequence, Animals, Cation Transport Proteins, Cell Line, Copper, Fungal Proteins, Glycosylation, Humans, Membrane Proteins, Microscopy, Fluorescence, Models, Molecular, Molecular Sequence Data, Mutation, Protein Binding, Protein Conformation, Two-Hybrid System Techniques
Amino Acid Sequence, Animals, Cation Transport Proteins, Cell Line, Copper, Fungal Proteins, Glycosylation, Humans, Membrane Proteins, Microscopy, Fluorescence, Models, Molecular, Molecular Sequence Data, Mutation, Protein Binding, Protein Conformation, Two-Hybrid System Techniques
Biochem. J.
Date: Mar. 15, 2003
PubMed ID: 12466020
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