MAMMALIAN COPPER TRANSPORT, HOMEOSTASIS, AND ITS DEFECTS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Copper serves as a cofactor of enzymes that are vital for normal growth and development. While copper is an essential micronutrient, excess accumulation of copper is detrimental. Genetic disorders in copper metabolism, copper-implicated degenerative diseases, and nutritional copper deficiency provide striking evidence that homeostatic copper metabolism is a critical physiological process. Given that copper transport across the plasma membrane is a central step in copper metabolism, defining the function, mode of action, and regulation of copper transporter could lead to better insights into copper homeostasis. Our studies, along with experiments by other investigators, have shown that the copper transporter 1 (Ctr1) family of integral membrane proteins, which is highly conserved in eukaryotes ranging from yeast to humans, is necessary for cellular copper uptake. However, the mechanism and regulation of Ctr1-mediated copper transport that is likely critical for optimal copper acquisition remains to be determined. To characterize molecular events in Ctr1 that are coupled with copper transport, we have employed a multi-disciplinary approach combining physiology, biochemistry, cell biology, biophysics, and genetics using yeast, mammalian cell lines, and mice. To directly relate molecular events in Ctr1 with its complex modes of regulation, we have developed a method for monitoring conformational changes in Ctr1 and protein-protein interactions of Ctr1 in situ. Our data shows that the conformation, activity, expression levels, and subcellular localization of Ctr1 are delicately controlled in a copper-dependent manner. This supports our central hypothesis that several layers of post-translational regulation of Ctr1 maintain optimal cellular copper acquisition.