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Gene Review

Rh4  -  Rhodopsin 4

Drosophila melanogaster

Synonyms: CG9668, DMELRH4, Dm Rh4, Dmel\CG9668, FBgn0003250, ...
 
 
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Disease relevance of Rh4

  • Suppression of constant-light-induced blindness but not retinal degeneration by inhibition of the rhodopsin degradation pathway [1].
  • rhodopsin mutations result in autosomal dominant retinitis pigmentosa (ADRP), the most frequent being Proline-23 substitution by histidine (RhoP23H) [2].
  • Rhodopsin formation in Drosophila is dependent on the PINTA retinoid-binding protein [3].
  • We propose that the sequestering of arrestin to membranes is a possible mechanism for retinal disease associated with previously identified rhodopsin alleles in humans [4].
  • Interactions between TcTex-1 and a diverse set of proteins such as the dynein intermediate chain, Fyn, DOC2, FIP1, the poliovirus receptor, CD155, and the rhodopsin cytoplasmic tail have been reported; yet, despite the broad range of targets, a consensus binding sequence remains uncertain [5].
 

High impact information on Rh4

  • The Rhesus blood-group antigens are defined by a complex association of membrane polypeptides that includes the non-glycosylated Rh proteins (RhD and RhCE) and the RHag glycoprotein, which is strictly required for cell surface expression of these antigens [6].
  • Despite their importance in transfusion medicine, the function of RhAG and Rh proteins remains unknown, except that their absence in Rh(null) individuals leads to morphological and functional abnormalities of erythrocytes, known as the Rh-deficiency syndrome [6].
  • The theory quantitatively describes the inactivation kinetics of activated rhodopsin in vivo and can be independently tested with molecular and spectroscopic data [7].
  • In Drosophila, the major rhodopsin Rh1 is synthesized in endoplasmic reticulum (ER)-bound ribosomes of the R1-R6 photoreceptor cells and is then transported to the rhabdomeres where it functions in phototransduction [8].
  • We have used P-element-mediated transformation to introduce the cloned Rh1 rhodopsin gene into the germ line of Drosophila and fully rescue the visual phenotype of mutant ninaE flies [9].
 

Chemical compound and disease context of Rh4

  • In a genetic screen for mutations that affect the biosynthesis of rhodopsin, we identified a novel CRAL-TRIO domain protein, prolonged depolarization afterpotential is not apparent (PINTA), which binds to all-trans-retinol [3].
 

Biological context of Rh4

  • Rh1 rhodopsin localizes to and is essential for the development and maintenance of the rhabdomere, the specialized membrane-rich organelle that serves as the site of phototransduction [10].
  • We show here that the distinction between the rhodopsins expressed in the two classes of ommatidia depends on a series of highly conserved homeodomain binding sites present in the rhodopsin promoters [11].
  • Numerous changes have occurred in these genes since the duplications, including the loss and/or gain of introns in the different genes and even within the Rh1 and Rh4 clades [12].
  • Evolution of gene position: chromosomal arrangement and sequence comparison of the Drosophila melanogaster and Drosophila virilis sina and Rh4 genes [13].
  • Studies of vertebrate rhodopsins have generated several conflicting proposals regarding the role of glycosylation in rhodopsin maturation [14].
 

Anatomical context of Rh4

  • We have identified a second Drosophila opsin gene, Rh4, which is expressed specifically in the ultraviolet-sensitive R7 photoreceptor cells [15].
  • In Drosophila, rhodopsin (Rh1), the most abundant rhodopsin, is glycosylated in the endoplasmic reticulum (ER) and requires its molecular chaperone, NinaA, for exit from the ER and transport through the secretory pathway [14].
  • Drac1 was localized in a specialization of the photoreceptor cortical actin cytoskeleton, which was lost in rhodopsin-null mutants [16].
  • Intriguingly, we have found a third isoform, dgqC, which is specifically and abundantly expressed in male gonads, and shares the divergent rhodopsin-binding exon of dgqA [17].
  • Vitamin A deprivation and the mutations also reduced the number of particles in the plasma membrane as in the rhabdomeric membrane, suggesting that both classes of membrane contain rhodopsin [18].
 

Associations of Rh4 with chemical compounds

  • Further, in transgenic flies expressing Rh4 as the major rhodopsin, 3-hydroxyretinal is the major retinoid in ninaG+, but a different retinoid profile is observed in ninaG(P330) [19].
  • These results indicate that the ninaG oxidoreductase acts in the biochemical pathway responsible for conversion of retinal to the rhodopsin chromophore, 3-hydroxyretinal [19].
  • Chimeric Rh1 pigments carrying individual substitutions of the cytoplasmic loops C2 and C3 and the C-terminus with the corresponding regions of Rho retained the ability to stimulate phototranduction in Drosophila, but failed to activate transducin [20].
  • We investigated the role of Rh1 glycosylation and Rh1/NinaA interactions under in vivo conditions by analyzing transgenic flies expressing Rh1 with isoleucine substitutions at each of the two consensus sites for N-linked glycosylation (N20I and N196I) [14].
  • Role of asparagine-linked oligosaccharides in rhodopsin maturation and association with its molecular chaperone, NinaA [14].
 

Other interactions of Rh4

 

Analytical, diagnostic and therapeutic context of Rh4

  • Molecular cloning of Drosophila Rh6 rhodopsin: the visual pigment of a subset of R8 photoreceptor cells [22].
  • Confocal microscopy suggests that RH4, one of the ultraviolet rhodopsins, may reside in the previously-described pale fluorescent R7 cells with RH3 in the yellow fluorescent R7 cells [23].
  • Proteins were resolved by polyacrylamide gel electrophoresis (PAGE) and subjected to immunoblot analysis using antibodies directed to rhodopsin, NinaA, Arr1, and Arr2 [24].
  • Novel Gq alpha isoform is a candidate transducer of rhodopsin signaling in a Drosophila testes-autonomous pacemaker [17].
  • 1 microm frozen sections were cut on an ultracryomicrotome, then stained with antibodies specific for rhodopsin or arrestin [25].

References

  1. Suppression of constant-light-induced blindness but not retinal degeneration by inhibition of the rhodopsin degradation pathway. Lee, S.J., Montell, C. Curr. Biol. (2004) [Pubmed]
  2. Rhodopsin maturation defects induce photoreceptor death by apoptosis: a fly model for RhodopsinPro23His human retinitis pigmentosa. Galy, A., Roux, M.J., Sahel, J.A., Léveillard, T., Giangrande, A. Hum. Mol. Genet. (2005) [Pubmed]
  3. Rhodopsin formation in Drosophila is dependent on the PINTA retinoid-binding protein. Wang, T., Montell, C. J. Neurosci. (2005) [Pubmed]
  4. A role for the light-dependent phosphorylation of visual arrestin. Alloway, P.G., Dolph, P.J. Proc. Natl. Acad. Sci. U.S.A. (1999) [Pubmed]
  5. Crystal structure of dynein light chain TcTex-1. Williams, J.C., Xie, H., Hendrickson, W.A. J. Biol. Chem. (2005) [Pubmed]
  6. The human Rhesus-associated RhAG protein and a kidney homologue promote ammonium transport in yeast. Marini, A.M., Matassi, G., Raynal, V., André, B., Cartron, J.P., Chérif-Zahar, B. Nat. Genet. (2000) [Pubmed]
  7. Arrestin binding determines the rate of inactivation of the G protein-coupled receptor rhodopsin in vivo. Ranganathan, R., Stevens, C.F. Cell (1995) [Pubmed]
  8. The cyclophilin homolog ninaA is required in the secretory pathway. Colley, N.J., Baker, E.K., Stamnes, M.A., Zuker, C.S. Cell (1991) [Pubmed]
  9. Ectopic expression of a minor Drosophila opsin in the major photoreceptor cell class: distinguishing the role of primary receptor and cellular context. Zuker, C.S., Mismer, D., Hardy, R., Rubin, G.M. Cell (1988) [Pubmed]
  10. The Drosophila rhodopsin cytoplasmic tail domain is required for maintenance of rhabdomere structure. Ahmad, S.T., Natochin, M., Artemyev, N.O., O'Tousa, J.E. FASEB J. (2007) [Pubmed]
  11. Otd/Crx, a dual regulator for the specification of ommatidia subtypes in the Drosophila retina. Tahayato, A., Sonneville, R., Pichaud, F., Wernet, M.F., Papatsenko, D., Beaufils, P., Cook, T., Desplan, C. Dev. Cell (2003) [Pubmed]
  12. Phylogeny and physiology of Drosophila opsins. Carulli, J.P., Chen, D.M., Stark, W.S., Hartl, D.L. J. Mol. Evol. (1994) [Pubmed]
  13. Evolution of gene position: chromosomal arrangement and sequence comparison of the Drosophila melanogaster and Drosophila virilis sina and Rh4 genes. Neufeld, T.P., Carthew, R.W., Rubin, G.M. Proc. Natl. Acad. Sci. U.S.A. (1991) [Pubmed]
  14. Role of asparagine-linked oligosaccharides in rhodopsin maturation and association with its molecular chaperone, NinaA. Webel, R., Menon, I., O'Tousa, J.E., Colley, N.J. J. Biol. Chem. (2000) [Pubmed]
  15. A second opsin gene expressed in the ultraviolet-sensitive R7 photoreceptor cells of Drosophila melanogaster. Montell, C., Jones, K., Zuker, C., Rubin, G. J. Neurosci. (1987) [Pubmed]
  16. Rescue of photoreceptor degeneration in rhodopsin-null Drosophila mutants by activated Rac1. Chang, H.Y., Ready, D.F. Science (2000) [Pubmed]
  17. Novel Gq alpha isoform is a candidate transducer of rhodopsin signaling in a Drosophila testes-autonomous pacemaker. Alvarez, C.E., Robison, K., Gilbert, W. Proc. Natl. Acad. Sci. U.S.A. (1996) [Pubmed]
  18. Freeze-fracture study of the Drosophila photoreceptor membrane: mutations affecting membrane particle density. Schinz, R.H., Lo, M.V., Larrivee, D.C., Pak, W.L. J. Cell Biol. (1982) [Pubmed]
  19. The Drosophila ninaG oxidoreductase acts in visual pigment chromophore production. Sarfare, S., Ahmad, S.T., Joyce, M.V., Boggess, B., O'Tousa, J.E. J. Biol. Chem. (2005) [Pubmed]
  20. Probing rhodopsin-transducin interaction using Drosophila Rh1-bovine rhodopsin chimeras. Natochin, M., Barren, B., Ahmad, S.T., O'tousa, J.E., Artemyev, N.O. Vision Res. (2006) [Pubmed]
  21. Transcript localization of four opsin genes in the three visual organs of Drosophila; RH2 is ocellus specific. Pollock, J.A., Benzer, S. Nature (1988) [Pubmed]
  22. Molecular cloning of Drosophila Rh6 rhodopsin: the visual pigment of a subset of R8 photoreceptor cells. Huber, A., Schulz, S., Bentrop, J., Groell, C., Wolfrum, U., Paulsen, R. FEBS Lett. (1997) [Pubmed]
  23. Vitamin A, visual pigments, and visual receptors in Drosophila. Lee, R.D., Thomas, C.F., Marietta, R.G., Stark, W.S. Microsc. Res. Tech. (1996) [Pubmed]
  24. Expression of rhodopsin and arrestin during the light-dark cycle in Drosophila. Hartman, S.J., Menon, I., Haug-Collet, K., Colley, N.J. Mol. Vis. (2001) [Pubmed]
  25. Epitope masking of rhabdomeric rhodopsin during endocytosis-induced retinal degeneration. Orem, N.R., Dolph, P.J. Mol. Vis. (2002) [Pubmed]
 
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