C. J. De Feo et al.: Tryptophan Scanning of Copper Transporters Hampton RY (2002) ER-associated degradation in protein quality control and cellular regulation. Curr Opin Cell Biol 14:476–482 Haremaki T, Fraser ST, Kuo YM, Baron MH, Weinstein DC (2007) Vertebrate Ctr1 coordinates morphogenesis and progenitor cell fate and regulates embryonic stem cell differentiation. Proc Natl Acad Sci USA 104:12029–12034 Hasler U, Crambert G, Horisberger JD, Geering K (2001) Structural and functional features of the transmembrane domain of the Na, K-ATPase beta subunit revealed by tryptophan scanning. J Biol Chem 276:16356–16364 Hassett R, Kosman DJ (1995) Evidence for Cu(II) reduction as a component of copper uptake by Saccharomyces cerevisiae. J Biol Chem 270:128–134 Holzer AK, Manorek GH, Howell SB (2006) Contribution of the major copper inﬂux transporter CTR1 to the cellular accumu- lation of cisplatin, carboplatin, and oxaliplatin. Mol Pharmacol 70:1390–1394 Huffman DL, O’Halloran TV (2000) Energetics of copper trafﬁcking between the Atx1 metallochaperone and the intracellular copper transporter, Ccc2. J Biol Chem 275:18611–18614 Huffman DL, O’Halloran TV (2001) Function, structure, and mechanism of intracellular copper trafﬁcking proteins. Annu Rev Biochem 70:677–701 Irizarry SN, Kutluay E, Drews G, Hart SJ, Heginbotham L (2002) Opening the KcsA K? channel: tryptophan scanning and complementation analysis lead to mutants with altered gating. Biochemistry 41:13653–13662 Ishida S, Lee J, Thiele DJ, Herskowitz I (2002) Uptake of the anticancer drug cisplatin mediated by the copper transporter Ctr1 in yeast and mammals. Proc Natl Acad Sci USA 99:14298–14302 Kim BE, Nevitt T, Thiele DJ (2008) Mechanisms for copper acquisition, distribution and regulation. Nat Chem Biol 4:176– 185 Klomp AE, Tops BB, Van Denberg IE, Berger R, Klomp LW (2002) Biochemical characterization and subcellular localization of human copper transporter 1 (hCTR1). Biochem J 364:497–505 Klomp AE, Juijn JA, van der Gun LT, van den Berg IE, Berger R, Klomp LW (2003) The N-terminus of the human copper transporter 1 (hCTR1) is localized extracellularly, and interacts with itself. Biochem J 370:881–889 Kuo YM, Zhou B, Cosco D, Gitschier J (2001) The copper transporter CTR1 provides an essential function in mammalian embryonic development. Proc Natl Acad Sci USA 98:6836–6841 Kuo MT, Chen HH, Song IS, Savaraj N, Ishikawa T (2007) The roles of copper transporters in cisplatin resistance. Cancer Metastasis Rev 26:71–83 Lamb AL, Wernimont AK, Pufahl RA, Culotta VC, O’Halloran TV, Rosenzweig AC (1999) Crystal structure of the copper chaper- one for superoxide dismutase. Nat Struct Biol 6:724–729 Lamb AL, Torres AS, O’Halloran TV, Rosenzweig AC (2001) Heterodimeric structure of superoxide dismutase in complex with its metallochaperone. Nat Struct Biol 8:751–755 Lee J, Prohaska JR, Thiele DJ (2001) Essential role for mammalian copper transporter Ctr1 in copper homeostasis and embryonic development. Proc Natl Acad Sci USA 98:6842–6847 Lee J, Pena MM, Nose Y, Thiele DJ (2002) Biochemical character- ization of the human copper transporter Ctr1. J Biol Chem 277:4380–4387 Li-Smerin Y, Hackos DH, Swartz KJ (2000) Alpha-helical structural elements within the voltage-sensing domains of a K? channel. J Gen Physiol 115:33–50 Lutsenko S, Barnes NL, Bartee MY, Dmitriev OY (2007) Function and regulation of human copper-transporting ATPases. Physiol Rev 87:1011–1046 Macreadie IG (2008) Copper transport and Alzheimer’s disease. Eur Biophys J 37:295–300 123 Maryon EB, Molloy SA, Kaplan JH (2007) O-Linked glycosylation at threonine 27 protects the copper transporter hCTR1 from proteolytic cleavage in mammalian cells. J Biol Chem 282: 20376–20387 Millhauser GL (2007) Copper and the prion protein: methods, struc- tures, function, and disease. Annu Rev Phys Chem 58:299–320 Mingarro I, Whitley P, Lemmon MA, von Heijne G (1996) Ala- insertion scanning mutagenesis of the glycophorin A transmem- brane helix: a rapid way to map helix–helix interactions in integral membrane proteins. Protein Sci 5:1339–1341 Monks SA, Needleman DJ, Miller C (1999) Helical structure and packing orientation of the S2 segment in the Shaker K? channel. J Gen Physiol 113:415–423 Mumberg D, Muller R, Funk M (1995) Yeast vectors for the controlled expression of heterologous proteins in different genetic backgrounds. Gene 156:119–122 Panchenko VA, Glasser CR, Mayer ML (2001) Structural similarities between glutamate receptor channels and K? channels examined by scanning mutagenesis. J Gen Physiol 117:345–360 Pena MM, Puig S, Thiele DJ (2000) Characterization of the Saccharomyces cerevisiae high afﬁnity copper transporter Ctr3. J Biol Chem 275:33244–33251 Petris MJ (2004) The SLC31 (Ctr) copper transporter family. Pﬂuegers Arch 447:752–755 Pettersen EF, Goddard TD, Huang CC, Couch GS, Greenblatt DM, Meng EC, Ferrin TE (2004) UCSF Chimera—a visualization system for exploratory research and analysis. J Comput Chem 25:1605–1612 Puig S, Thiele DJ (2002) Molecular mechanisms of copper uptake and distribution. Curr Opin Chem Biol 6:171–180 Puig S, Lee J, Lau M, Thiele DJ (2002) Biochemical and genetic analyses of yeast and human high afﬁnity copper transporters suggest a conserved mechanism for copper uptake. J Biol Chem 277:26021–26030 Rae TD, Schmidt PJ, Pufahl RA, Culotta VC, O’Halloran TV (1999) Undetectable intracellular free copper: the requirement of a copper chaperone for superoxide dismutase. Science 284:805– 808 Rees EM, Thiele DJ (2007) Identiﬁcation of a vacuole-associated metalloreductase and its role in Ctr2-mediated intracellular copper mobilization. J Biol Chem 282:21629–21638 Romisch K (2005) Endoplasmic reticulum-associated degradation. Annu Rev Cell Dev Biol 21:435–456 Safaei R (2006) Role of copper transporters in the uptake and efﬂux of platinum containing drugs. Cancer Lett 234:34–39 Sharp LL, Zhou J, Blair DF (1995) Features of MotA proton channel structure revealed by tryptophan-scanning mutagenesis. Proc Natl Acad Sci USA 92:7946–7950 Song IS, Savaraj N, Siddik ZH, Liu P, Wei Y, Wu CJ, Kuo MT (2004) Role of human copper transporter Ctr1 in the transport of platinum-based antitumor agents in cisplatin-sensitive and cisplatin-resistant cells. Mol Cancer Ther 3:1543–1549 Turski ML, Thiele DJ (2007) Drosophila Ctr1A functions as a copper transporter essential for development. J Biol Chem 282:24017– 24026 Zhou H, Thiele DJ (2001) Identiﬁcation of a novel high afﬁnity copper transport complex in the ﬁssion yeast Schizosaccharo- myces pombe. J Biol Chem 276:20529–20535 Zhou H, Cadigan KM, Thiele DJ (2003) A copper-regulated transporter required for copper acquisition, pigmentation, and speciﬁc stages of development in Drosophila melanogaster. J Biol Chem 278:48210–48218 Zimnicka AM, Maryon EB, Kaplan JH (2007) Human copper transporter hCTR1 mediates basolateral uptake of copper into enterocytes: implications for copper homeostasis. J Biol Chem 282:26471–26480 123