Rab6 Regulation of Rhodopsin Transport inDrosophila

Abstract

Rab6 is a GTP binding protein that regulates vesicular trafficking within the Golgi and post-Golgi compartments. We overexpressed wild-type, a GTPase defective (Q71L), and a guanine nucleotide binding defective (N125I) Rab6 protein inDrosophila photoreceptors to assess the in vivorole of Rab6 in the trafficking of rhodopsin and other proteins. Expression of Drab6Q71L greatly reduced the steady state levels of two rhodopsins, Rh1 and Rh3, whereasDrab6wt and Drab6N125I showed weaker effects. Analysis of a strain carrying Rh1 rhodopsin under a heat shock promoter showed thatDrab6Q71L, but notDrab6wt or Drab6N125I, prevents the maturation of rhodopsin beyond an immature 40 kDa form. Drab6Q71L is a GTPase defective mutant, indicating that anterograde transport of rhodopsin requires Rab6 GTPase function. The three Drab6 strains had no effect on the expression of several other photoreceptor proteins. TheDrab6Q71L photoreceptors show marked histological defects at young ages and degenerate over a two week time span. These results establish that rhodopsin is transported via a Rab6 regulated pathway and that defects in trafficking pathways lead to retinal degeneration. Rab6 is a GTP binding protein that regulates vesicular trafficking within the Golgi and post-Golgi compartments. We overexpressed wild-type, a GTPase defective (Q71L), and a guanine nucleotide binding defective (N125I) Rab6 protein inDrosophila photoreceptors to assess the in vivorole of Rab6 in the trafficking of rhodopsin and other proteins. Expression of Drab6Q71L greatly reduced the steady state levels of two rhodopsins, Rh1 and Rh3, whereasDrab6wt and Drab6N125I showed weaker effects. Analysis of a strain carrying Rh1 rhodopsin under a heat shock promoter showed thatDrab6Q71L, but notDrab6wt or Drab6N125I, prevents the maturation of rhodopsin beyond an immature 40 kDa form. Drab6Q71L is a GTPase defective mutant, indicating that anterograde transport of rhodopsin requires Rab6 GTPase function. The three Drab6 strains had no effect on the expression of several other photoreceptor proteins. TheDrab6Q71L photoreceptors show marked histological defects at young ages and degenerate over a two week time span. These results establish that rhodopsin is transported via a Rab6 regulated pathway and that defects in trafficking pathways lead to retinal degeneration. Members of the Rab family of small GTPases are localized in distinct subcellular compartments (1Novick P. Brennwald P. Cell. 1993; 75: 597-601Abstract Full Text PDF PubMed Scopus (316) Google Scholar), and within these compartments they regulate vesicular trafficking by cycling between GTP- and GDP-bound forms (2Zerial M. Stenmark H. Curr. Opin. Cell Biol. 1993; 5: 613-620Crossref PubMed Scopus (343) Google Scholar). A general model of Rab function has emerged in which a complex of Rab-GDP and guanine nucleotide dissociation inhibitor (GDI) 1The abbreviations used are: GDIguanine nucleotide dissociation inhibitorRT-PCRreverse transcription-polymerase chain reactionERGelectroretinographyPDAprolonged depolarizing afterpotentialERendoplasmic reticulum. is maintained in the cytosol. On binding of this complex to the donor membrane, GDI is displaced and GDP is exchanged for GTP. Rab-GTP is recruited onto the transport vesicle, which buds from the donor membrane and then associates with the target membrane. The Rab-GTP is thought to mediate fusion of the vesicle through interactions with effector molecules on the target membrane. It is not known whether GTP hydrolysis of the Rab-GTP is required for vesicle fusion or occurs after fusion. After GTP hydrolysis, Rab-GDP is retrieved from the target membrane by GDI and recycled to the donor membrane (3Novick P. Zerial M. Curr. Opin. Cell Biol. 1997; 9: 496-504Crossref PubMed Scopus (666) Google Scholar, 4Pfeffer S. Curr. Opin. Cell Biol. 1994; 6: 522-526Crossref PubMed Scopus (296) Google Scholar, 5Nuoffer C. Balch W.E. Annu. Rev. Biochem. 1994; 63: 949-990Crossref PubMed Scopus (375) Google Scholar). guanine nucleotide dissociation inhibitor reverse transcription-polymerase chain reaction electroretinography prolonged depolarizing afterpotential endoplasmic reticulum. The study of point mutations in several rab genes affecting amino acids essential for guanine nucleotide interactions has documented the importance of the Rab-guanine nucleotide interactions in Rab function (6Tisdale E.J. Bourne J.R. Khosravi-Far R. Der C.J. Balch W.E. J. Cell Biol. 1992; 119: 749-761Crossref PubMed Scopus (423) Google Scholar, 7McConlogue L. Castellano F. deWit C. Schenk D. Maltese W.A. J. Biol Chem. 1996; 271: 1343-1348Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar, 8Martinez O. Antony C. Pehau-Arnaudet G. Berger E.G. Salamero J. Goud B. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 1828-1833Crossref PubMed Scopus (147) Google Scholar). The Rab6 protein is likely involved in intra-Golgi transport. A GTPase defective Rab6 greatly reduced transport of the proteins between cis/medial and late Golgi compartments in mammalian cell culture (9Martinez O. Schimdt A. Salamero J. Hoflack B. Roa M. Goud B. J. Cell Biol. 1994; 127: 1575-1588Crossref PubMed Scopus (221) Google Scholar). More recently, Martinez et al. (8Martinez O. Antony C. Pehau-Arnaudet G. Berger E.G. Salamero J. Goud B. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 1828-1833Crossref PubMed Scopus (147) Google Scholar) found that overexpression of wild-type Rab6 and a GTPase-defective Rab6 redistributed a trans-Golgi protein to the ER membrane compartment. Biochemical studies using specialized cells, however, have suggested a role for Rab6 in post-Golgi transport. Rab6 is associated with post-Golgi vesicles in Torpedo marmorata electrocytes (10Jasmin B. Goud B. Camus G. Cartaud J. Neuroscience. 1992; 49: 849-855Crossref PubMed Scopus (27) Google Scholar), hypothalamic neuronal cells (11Tixier-Vidal A. Barret A. Picart R. Mayau V. Vogt D. Wiedenmann B. Goud B. J. Cell Sci. 1993; 105: 935-947PubMed Google Scholar), and frog retinal cells (12Deretic D. Papermaster D.S. J. Cell Sci. 1993; 106: 803-813PubMed Google Scholar). The studies with frog retinal cells suggested that the Rab6 protein is associated with rhodopsin-containing vesicles that exit from thetrans-Golgi on their way to the rod outer segment. The Drosophila photoreceptor provides an excellent experimental system to study Rab6 function in rhodopsin membrane trafficking, given the availability of mutations in rhodopsin and other genes that impede rhodopsin maturation. Many of these mutations result in age-dependent degeneration of photoreceptors, suggesting that correct rhodopsin trafficking is critical to maintenance of photoreceptor stability. Some human retinal diseases caused by rhodopsin mutations, may also be due to improper rhodopsin trafficking within the photoreceptor (13Sung C.-H. Makino C. Baylor D.A. Nathans J. J. Neurosci. 1994; 14: 5818-5833Crossref PubMed Google Scholar). In addition, an inherited form of choroideremia results from a defective Rab escort protein-1, establishing that defects in Rab protein function are involved in other human degenerative diseases (14Seabra M.C. Ho Y.K. Anant J.S. J. Biol. Chem. 1995; 270: 24420-24427Abstract Full Text Full Text PDF PubMed Scopus (184) Google Scholar). We established an in vivo system to study the role of Rab6 in the trafficking of rhodopsin and other photoreceptor proteins. Our results suggest that Rab6 is required for anterograde rhodopsin transport through the ER-Golgi complex. Further, defects in Rab6 trafficking also trigger retinal degeneration, strengthening the tie between defects in the rhodopsin maturation pathway and photoreceptor degeneration. Degenerate primers based on the conserved DTAGQ and NKXD sequence motifs found in all Rab proteins were used to RT-PCR amplify rab sequences from totalDrosophila RNA. RNA was isolated following methods of Cathala et al. (15Cathala G. Sacouret B. Mendez B. West M. Karin M. Martial J.A. Baxter J.D. DNA. 1983; 2: 329-335Crossref PubMed Scopus (1229) Google Scholar). RT-PCR reaction was performed as specified by the RT-PCR reaction kit manufacturer (Perkin-Elmer). The 170-base pair fragments recovered from these reactions were cloned and sequenced to identify the Drosophila rab6 sequence (Drab6). The 170-base pair fragment of Drab6 was then used to isolate the entire rab6 gene from aDrosophila genomic library. In situhybridizations, carried out as described by Ashburner (16Ashburner M. Drosophila: A Laboratory Manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY1989Google Scholar), placed the gene at 33C/D on the standard Drosophila salivary chromosome map. Site-directed mutagenesis was used to createDrab6N125I (AAC to ATC) andDrab6Q71L (CAG to CTG). The coding sequence of the two mutants and Drab6wt were placed under the control of the ninaE promoter and inserted in a P-element transformation vector (17Rubin G.M. Spradling A.C. Nucleic Acids Res. 1983; 11: 6341-6351Crossref PubMed Scopus (332) Google Scholar). Drosophila transgenic flies were made by standard means (18Spradling A.C. Roberts D.B. Drosophila: A Practical Approach. IRL Press Limited, Oxford, England1986: 175-196Google Scholar) using the null mutantninaE oI17 as the recipient strain. Four independent lines were obtained for Drab6wt andDrab6N125I and two independent lines were obtained for Drab6Q71L. All lines for each construct showed similar levels of Rab6 expression and rhodopsin defects as described in this paper. A polyclonal antibody toDrosophila Rab6 was generated using the GEX glutathioneS-transferase system (19Smith D.B. Johnson K.S. Gene ( Amst. ). 1988; 67: 31-40Crossref PubMed Scopus (5047) Google Scholar). To generate the antibody, a 243-base pair region coding for a C-terminal region of Rab6 (amino acids 129–208) was placed in the pGEX-3 vector. The fusion protein was collected on glutathione-agarose beads and then recovered from the beads by eluting in 8 m urea, 1 mm glycine, 1 mm EDTA, 100 mm β-mercaptoethanol, 0.1m Tris, pH 8.0. The fusion protein was dialyzed overnight in 20 mm Tris, pH 8.0, and used to immunize mice. Proteins from fly heads were extracted in 60 mm Tris, pH 6.8, 25% glycerol, 2% SDS, 14.4 mm β-mercaptoethanol, and 0.1% bromphenol blue, separated by SDS-polyacrylamide gel electrophoresis (20Laemmli U.K. Nature. 1970; 227: 680-685Crossref PubMed Scopus (207537) Google Scholar) on 4–15%, 10%, or 12% gels, and transferred onto nitrocellulose membranes (Amersham Pharmacia Biotech) in 19 mm Tris, 150 mm glycine, 20% methanol. Proteins were detected using the polyclonal antibodies directed against Rh1 or Rh3 opsin, 2T. Washburn, M. Serikaku, and J. O'Tousa, unpublished data. RdgB (21Vihtelic T.S. Goebl M. Milligan S. O'Tousa J.E. Hyde D.R. J. Cell Biol. 1993; 122: 1013-1022Crossref PubMed Scopus (159) Google Scholar), Trp (22Montell C. Rubin G.M. Neuron. 1989; 2: 1313-1323Abstract Full Text PDF PubMed Scopus (872) Google Scholar), and NinaC (23Montell C. Rubin G.M. Cell. 1988; 52: 757-772Abstract Full Text PDF PubMed Scopus (234) Google Scholar). Protein was detected using the ECL system (Amersham Pharmacia Biotech). To analyze the transient expression of rhodopsin, we used a stock designated hs-ninaE-hsv tag 14. This stock contained an HSV (epitope identified in herpes simplex virus glycoprotein D)-tagged rhodopsin under the heat shock promoter (24Kurada P. Tonini T.D. Serikaku M.A. Piccini J.P. O'Tousa J.E. Visual Neurosci. 1998; 15: 693-700Crossref PubMed Scopus (22) Google Scholar). Flies heterozygous for the tagged rhodopsin and the respective Drab6 P-transgene were heat shocked for 1 h at 37 °C and placed at room temperature (22 °C) for the indicated time. Protein separation, transfer, and detection were performed as stated above, using a monoclonal antibody directed against the HSV tag (Novagen Corp.). Electroretinography (ERG) recordings (as described in Larrivee et al. (25Larrivee D.C. Conrad S.K. Stephenson R.S. Pak W.L. J. Gen. Physiol. 1981; 78: 521-545Crossref PubMed Scopus Google were performed on flies in a was performed as described by and O'Tousa O'Tousa J.E. 1992; PubMed Google Scholar). All were and maintained in a The Drab6wt andDrab6N125I flies were flies were heterozygous flies heterozygous for rhodopsin were also and the results not We used a to a study of Drosophila rab6 and identified the rab6 gene et al. A. F. 1997; PubMed Scopus Google Scholar). We two the GTPase defective and the guanine nucleotide binding defective by in These two mutants and the wild-type coding sequences were placed under the control of the ninaE promoter to and levels of expression in the Drosophila of photoreceptor cells D. Rubin G.M. PubMed Google Scholar). Protein Rab6 antibody that transgenic flies carrying these genes made of the Rab6 proteins The of the Rab6 protein in the transgenic flies a that in control wild-type to a Rab6 protein (9Martinez O. Schimdt A. Salamero J. Hoflack B. Roa M. Goud B. J. Cell Biol. 1994; 127: 1575-1588Crossref PubMed Scopus (221) Google Scholar). The form of Rab6 was also in these transgenic We that Rab6 protein was detected in flies in wild-type control levels of Rab6 protein protein in Drab6N125I, and protein in was in the other transgenic To for defects in photoreceptor function of expression of these Rab6 we the by All strains show a to A prolonged depolarizing afterpotential is in the on to a of rhodopsin is to an form W.L. to the Scholar). flies generate a and Drab6N125I flies show a in the Drab6Q71L flies a the importance of rhodopsin levels in a these results suggested that Drab6wt andDrab6N125I have on rhodopsin and Drab6Q71L flies levels of protein levels were by to assess the of the levels are reduced in Drab6Q71L of is a in and Drab6N125I flies and of wild-type levels in Drab6 and Drab6 is the of rhodopsin levels from protein of flies All flies were and heterozygous for a wild-type rhodopsin was detected by a polyclonal rhodopsin The of protein levels are from of two independent We the of the Drab6 strains in an experimental to defects in the rhodopsin maturation pathway (24Kurada P. Tonini T.D. Serikaku M.A. Piccini J.P. O'Tousa J.E. Visual Neurosci. 1998; 15: 693-700Crossref PubMed Scopus (22) Google Scholar, J.A. Proc. Natl. Acad. Sci. U. S. A. 1995; PubMed Scopus Google Scholar) also In these flies carried a rhodopsin gene tagged by an HSV from a heat shock Expression of this rhodopsin gene occurs a 37 °C heat the of rhodopsin a time to be the study we strains carrying the heat rhodopsin gene and each of the three Drab6 A strain the heat rhodopsin gene but construct as the control in these In the of heat no rhodopsin be detected in protein h following the heat the rhodopsin is detected as a as as several h after the rhodopsin is in the form but is also detected in h after the heat of the rhodopsin is found in the form This form has the as the of rhodopsin found in flies the rhodopsin from the ninaE we the form. The strains and Drab6N125I genes had the as the control strain The Drab6Q71L however, showed defects in rhodopsin maturation h after heat the of the rhodopsin was detected in the as from the of the other at and h after heat the rhodopsin as the The establish that the Drab6Q71L is defective in the immature rhodopsin the form. In Drosophila are in of the photoreceptor To the of the Drab6 on a rhodopsin, we the Rh3 rhodopsin in photoreceptor cells R. R. D. Rubin G.M. M. J. Neurosci. 1992; PubMed Google Scholar). of these strains showed that Rh3 protein levels were reduced in all three Drab6 transgenic strains with with expression of the Rh1 Rh3 levels were reduced in the Drab6Q71L with the other two lines a but of We the protein levels of two other photoreceptor membrane proteins involved in to whether effect was to RdgB is a membrane protein that is localized to the photoreceptor (21Vihtelic T.S. Goebl M. Milligan S. O'Tousa J.E. Hyde D.R. J. Cell Biol. 1993; 122: 1013-1022Crossref PubMed Scopus (159) Google Scholar), and Trp is a protein that with rhodopsin in the Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). RdgB Trp protein levels were in Drab6 strain. the protein levels of the photoreceptor proteins were not was carried out to assess the in photoreceptor caused by overexpression of Rh1 rhodopsin also genes in this The in not the Drab6 and as a control in all control photoreceptors are in A. Drab6wt andDrab6N125I photoreceptors not are similar in to the Drab6Q71L flies however, show a marked in the The of the in the Drab6Q71L is similar in to the the wild-type are D.S. Pak W.L. J. 1992; PubMed Scopus Google Scholar). Drab6Q71L cells an of membranes at the of the in Some photoreceptors show membranes in is the of membranes The of on Visual Press, Google Scholar) within the cell in on flies indicated that overexpression of all three Drab6 genes retinal degeneration. A of an of a is in not for Drab6wt Some photoreceptors of all the strains membranes marked in A of this study was to the role of Rab6 in rhodopsin maturation. Protein and established flies 12% of the wild-type steady state levels of Drab6wt and Drab6N125I flies of the wild-type rhodopsin The in the be to the in rhodopsin indicating that overexpression of the Rab6 proteins not have a effect on the of these photoreceptor Analysis of rhodopsin transport using a heat promoter that in wild-type, andDrab6N125I photoreceptors, rhodopsin to form within In rhodopsin maturation is in beyond the form. established that the rhodopsin is a found within the The rhodopsin requires M.A. Cell. 67: Full Text PDF PubMed Scopus Google Scholar) and retinal H. M. F. Neuron. 1993; Full Text PDF PubMed Scopus Google Scholar, A. U. R. J. Cell Biol. 1994; 63: Google Scholar) to exit the Our results show that rhodopsin transport to the or Golgi that the which on the rhodopsin Annu. Rev. Cell Biol. 1989; 5: PubMed Scopus Google Scholar, J.E. L. J. PubMed Scopus Google Scholar). These results are with a role of Rab6 in intra-Golgi transport. we have no suggesting Rab6 in post-Golgi as suggested by a study on frog retinal cells (12Deretic D. Papermaster D.S. J. Cell Sci. 1993; 106: 803-813PubMed Google Scholar), not out a independent role of A study showed that transient expression of protein prevents rhodopsin maturation beyond the F. S. J. Cell Sci. 1997; Google Scholar), similar to the in It is that mutants of the two Rab proteins in photoreceptor to similar of rhodopsin maturation. rhodopsin likely in a form as from the ER to the or Golgi of the chain is thought to the and Rab6 may be required in these The expression of Rh3 rhodopsin was also reduced in the Drab6Q71L and were in the two other Drab6 On the other of the Drab6 strains the levels of other photoreceptor proteins These results suggest that rhodopsin transport is to defects in the with maturation pathways for other photoreceptor membrane proteins. that RdgB and Trp are transported via the Rab6 pathway but are maintained at is the of these proteins is of these likely the and of vivo of function rab6 with point mutations of rab6 (9Martinez O. Schimdt A. Salamero J. Hoflack B. Roa M. Goud B. J. Cell Biol. 1994; 127: 1575-1588Crossref PubMed Scopus (221) Google Scholar) and other rab genes (6Tisdale E.J. Bourne J.R. Khosravi-Far R. Der C.J. Balch W.E. J. Cell Biol. 1992; 119: 749-761Crossref PubMed Scopus (423) Google H. O. A. J. Zerial M. J. 1994; PubMed Scopus Google Scholar), the to prevents GTP the protein be to GTP. Drab6Q71L is a inhibitor of rhodopsin protein which is with the of this in other Rab6 studies (8Martinez O. Antony C. Pehau-Arnaudet G. Berger E.G. Salamero J. Goud B. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 1828-1833Crossref PubMed Scopus (147) Google Scholar, O. Schimdt A. Salamero J. Hoflack B. Roa M. Goud B. J. Cell Biol. 1994; 127: 1575-1588Crossref PubMed Scopus (221) Google Scholar). GTP hydrolysis is required for vesicle as for L. Roa M. F. J. 1994; PubMed Scopus Google is to the fusion of vesicles with their target membrane. Our results that form rhodopsin transport is with a role for GTP hydrolysis to anterograde transport of Rab6 in GTP form be a of the as by Martinez et al. (8Martinez O. Antony C. Pehau-Arnaudet G. Berger E.G. Salamero J. Goud B. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 1828-1833Crossref PubMed Scopus (147) Google Scholar, O. Schimdt A. Salamero J. Hoflack B. Roa M. Goud B. J. Cell Biol. 1994; 127: 1575-1588Crossref PubMed Scopus (221) Google Scholar). to this Drab6Q71L the of transport and the anterograde in of protein transport. this model was to results that has similar as that were not in We also documented an of Rh1 and Rh3 rhodopsin expression in the Drab6wt andDrab6N125I the heat shock that Drab6wt andDrab6N125I have or no on the maturation of the to the form of Rh1 the of Drab6wt andDrab6N125I is distinct from that The Drab6wt and Drab6N125I proteins have an effect on of rhodopsin but is also that the in rhodopsin is a of associated with the overexpression of these proteins. All Rab proteins to be C. Cell Biol. 1992; 2: Full Text PDF PubMed Scopus Google Scholar). we Rab6 in photoreceptors, of the protein is The to the of Rab6 found in these flies that overexpression has the Rab pathway for the of all Rab proteins J.A. D.S. C. J. Cell Biol. 1992; PubMed Scopus Google Scholar). overexpression of Rab6 may also the and the of other Rab proteins. the defects in photoreceptors or may not be to the Rab6 It is that Drab6wt andDrab6N125I have similar effects. The to is thought to a in guanine nucleotide In mammalian cell the to of and proteins show similar effect on as for the to mutations (6Tisdale E.J. Bourne J.R. Khosravi-Far R. Der C.J. Balch W.E. J. Cell Biol. 1992; 119: 749-761Crossref PubMed Scopus (423) Google Scholar, L. Roa M. F. J. 1994; PubMed Scopus Google Scholar). On the other the to in rab6 L. Castellano F. deWit C. Schenk D. Maltese W.A. J. Biol Chem. 1996; 271: 1343-1348Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar). The of a in studies not result from protein protein show levels of this It that the of of nucleotide is to in the rab6 of form of Rab6 caused retinal degeneration, but the and of degeneration the form of young photoreceptors show that from Drab6wt andDrab6N125I The is a by the This is with ninaE D.S. Pak W.L. J. 1992; PubMed Scopus Google Scholar, J.E. D.S. Pak W.L. J. 1989; 6: PubMed Scopus Google M.A. Cell. 67: Full Text PDF PubMed Scopus Google Scholar), H. Pak W.L. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, J.A. D.S. C. J. Cell Biol. 1992; PubMed Scopus Google Scholar), as as A flies J.S. L. Res. PubMed Scopus Google Scholar). All these flies reduced rhodopsin suggesting that the reduced of the in is likely the result of rhodopsin maturation. The Drab6Q71L photoreceptors other an of membranes within the as as membranes thought to membrane The of on Visual Press, Google Scholar). et al. F. S. J. Cell Sci. 1997; Google Scholar) documented a similar in the Drosophila results are also obtained in mammalian cell Martinez et al. (8Martinez O. Antony C. Pehau-Arnaudet G. Berger E.G. Salamero J. Goud B. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 1828-1833Crossref PubMed Scopus (147) Google Scholar) documented that overexpression of the the of ER and Golgi membrane and of the are in other studies using to of Rab proteins D. C. G. J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar). the membrane documented photoreceptors may result from Golgi and the defects in rhodopsin maturation may be a of this On the other are not with a in ER-Golgi transport in Drab6Q71L photoreceptors, as these photoreceptors and other membrane proteins are detected at rhodopsin mutants age-dependent retinal degeneration as a result of defects in rhodopsin transport J.A. Proc. Natl. Acad. Sci. U. S. A. 1995; PubMed Scopus Google Scholar, P. O'Tousa J.E. Neuron. 1995; 14: Full Text PDF PubMed Scopus Google Scholar). We this study to the role of Rab6 in rhodopsin transport and to an in vivo experimental system to study the trafficking of Our results establish the importance of trafficking in rhodopsin and maintenance of photoreceptor and function. We for with and Tonini for in of the transgenic Drosophila for with and for their Rab6 sequence to and Hyde for for the Rh3 transgenic and and for critical of this