for initial training and access to confocal microscopy. We thank Claude Desplan for helpful discussions, Gunter Merdes and Armin Huber for advise and some fly lines, and Dimitris Liakopoulos for support in confocal microscopy. Author Contributions Conceived and designed the experiments: VP IS. Performed the experiments: VP IK JK-L MR. Analyzed the data: VP IS. Wrote the paper: VP IS. 7 April 2011 | Volume 6 | Issue 4 | e18478 Eukaryotic Membrane Protein Expression 12. Fraley ME Positive allosteric modulators of the metabotropic glutamate receptor 2 for the treatment of schizophrenia. Expert Opin Ther Pat 19: 1259275. 13. Griffith DA, Delipala C, Leadsham J, Jarvis SM, Oesterhelt D A novel yeast expression CI-1011 system for the overproduction of quality-controlled membrane proteins. FEBS Lett 553: 450. 14. Eroglu C, Cronet P, Panneels V, Beaufils P, Sinning I Functional reconstitution of purified metabotropic glutamate receptor expressed in the fly eye. EMBO Rep 3: 49196. 15. Eroglu C, Brugger B, Wieland F, Sinning I Glutamate-binding affinity of Drosophila metabotropic glutamate receptor is modulated by association with lipid rafts. Proc Natl Acad Sci U S A 100: 102190224. 16. Panneels V, Sinning I Membrane protein expression in the eyes of transgenic flies. Methods Mol Biol 601: 13547. 17. Brand AH, Perrimon N Targeted gene expression as a means of altering cell fates and generating dominant phenotypes. Development 118: 40115. 18. Drew D, Newstead S, Sonoda Y, Kim H, von Heijne G, et al. GFP-based optimization scheme for the overexpression and purification of eukaryotic membrane proteins in Saccharomyces cerevisiae. Nat Protoc 3: 78498. 19. Waldo GS, Standish BM, Berendzen J, Terwilliger TC Rapid proteinfolding assay using green fluorescent protein. Nat Biotechnol 17: 69195. 20. Zuker CS The biology of vision of Drosophila. Proc Natl Acad Sci U S A 93: 57176. 21. Hardie RC Phototransduction in Drosophila melanogaster. J Exp Biol 204: 3403409. 22. Vought BW, Salcedo E, Chadwell LV, Britt SG, Birge RR, et al. Characterization of the primary photointermediates of Drosophila rhodopsin. Biochemistry 39: 141284137. 23. Foord SM, Bonner TI, Neubig RR, Rosser EM, Pin JP, et al. International Union of Pharmacology. XLVI. G protein-coupled receptor list. Pharmacol Rev 57: 27988. 24. Oksche A, Rosenthal W The molecular basis of nephrogenic diabetes insipidus. J Mol Med 76: 32637. 25. Grisshammer R, Tate CG Overexpression of integral membrane proteins for structural studies. Q Rev Biophys 28: 31522. 26. Nazari R, Joshi S CCR5 as target for HIV-1 gene therapy. Curr Gene Ther 8: 26472. 27. Paulsen R, Schwemer J Biogenesis of blowfly photoreceptor membranes is regulated by 11-cis-retinal. Eur J Biochem 137: 60914. 28. Koenig J, Merriam J Autosomal ERG mutants. Dros Inf Serv 42: 501. 29. Kumar JP, Ready DF Rhodopsin plays an essential structural role in Drosophila photoreceptor development. Development 121: 4359370. 30. Kateriya S, Nagel G, Bamberg E, Hegemann P ��Vision��in single-celled algae. News Physiol Sci 19: 13337. 31. Ellis MC, O’Neill EM, Rubin GM Expression of Drosophila glass protein and evidence for negative regulation of its activity in non-neuronal cells by another DNA-binding protein. Development 119: 85565. 32. Moses K, Ellis MC, Rubin GM The glass gene encodes a zinc-finger protein required by Drosophila photoreceptor cells. Nature 340: 53136. 33. Moses K, Rubin GM Glass encodes a site-specific DNA-binding protein that is regulated in respon for initial training and access to confocal microscopy. We thank Claude Desplan for helpful discussions, Gunter Merdes and Armin Huber for advise and some fly lines, and Dimitris Liakopoulos for support in confocal microscopy. Author Contributions Conceived and designed the experiments: VP IS. Performed the experiments: VP IK JK-L MR. Analyzed the data: VP IS. Wrote the paper: VP IS. 7 April 2011 | Volume 6 | Issue 4 | e18478 Eukaryotic Membrane Protein Expression 12. Fraley ME Positive allosteric modulators of the metabotropic glutamate receptor 2 for the treatment of schizophrenia. Expert Opin Ther Pat 19: 1259275. 13. Griffith DA, Delipala C, Leadsham J, Jarvis SM, Oesterhelt D A novel yeast expression system for the overproduction of quality-controlled membrane proteins. FEBS Lett 553: 450. 14. Eroglu C, Cronet P, Panneels V, Beaufils P, Sinning I Functional reconstitution of purified metabotropic glutamate receptor expressed in the fly eye. EMBO Rep 3: 49196. 15. Eroglu C, Brugger B, Wieland F, Sinning I Glutamate-binding affinity of Drosophila metabotropic glutamate receptor is modulated by association with lipid rafts. Proc Natl Acad Sci U S A 100: 102190224. 16. Panneels V, Sinning I Membrane protein expression in the eyes of transgenic flies. Methods Mol Biol 601: 13547. 17. Brand AH, Perrimon N Targeted gene expression as a means of altering cell fates and generating dominant phenotypes. Development 118: 40115. 18. Drew D, Newstead S, Sonoda Y, Kim H, von Heijne G, et al. GFP-based optimization scheme for the overexpression and purification of eukaryotic membrane proteins in Saccharomyces cerevisiae. Nat Protoc 3: 78498. 19. Waldo GS, Standish BM, Berendzen J, Terwilliger TC Rapid proteinfolding assay using 
green fluorescent protein. Nat Biotechnol 17: 69195. 20. Zuker CS The biology of vision of Drosophila. Proc Natl Acad Sci U S A 93: 57176. 21. Hardie RC Phototransduction in Drosophila melanogaster. J Exp Biol 204: 3403409. 22. Vought BW, Salcedo E, Chadwell LV, Britt SG, Birge RR, et al. Characterization of the primary photointermediates of Drosophila rhodopsin. Biochemistry 39: 141284137. 23. Foord SM, Bonner TI, Neubig RR, Rosser EM, Pin JP, et al. International Union of Pharmacology. XLVI. G protein-coupled receptor list. Pharmacol Rev 57: 27988. 24. Oksche A, Rosenthal W The molecular basis of nephrogenic diabetes insipidus. J Mol Med 76: 32637. 25. Grisshammer R, Tate CG Overexpression of integral membrane proteins for structural studies. Q Rev Biophys 28: 31522. 26. Nazari R, Joshi S CCR5 as target for HIV-1 gene therapy. Curr Gene Ther 8: 26472. 27. Paulsen R, Schwemer J Biogenesis of blowfly photoreceptor membranes is regulated by 11-cis-retinal. Eur J Biochem 137: 60914. 28. Koenig J, Merriam J Autosomal ERG mutants. Dros Inf Serv 42: 501. 29. Kumar JP, Ready DF Rhodopsin plays an essential structural role in Drosophila photoreceptor development. Development 121: 4359370. 30. Kateriya S, Nagel G, Bamberg E, Hegemann P ��Vision��in single-celled algae. News Physiol Sci 19: 13337. 31. Ellis MC, O’Neill EM, Rubin GM Expression of Drosophila glass protein and evidence for negative regulation of its activity in non-neuronal cells by another DNA-binding protein. Development 119: 85565. 32. Moses K, Ellis MC, Rubin GM The glass gene encodes a zinc-finger protein required by Drosophila photoreceptor cells. Nature 340: 53136. 33. Moses K, Rubin GM Glass encodes a site-specific DNA-binding protein that is regulated in respon