Renewal of visual pigment in photoreceptors of the blowfly

Schwemer, Joachim

doi:10.1007/bf00610167

Cited by 76 publications

(53 citation statements)

References 40 publications

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“…Rhodopsin, like most of the other proteins required for phototransduction, is synthesized initially at a high rate during late pupal life and continues into adulthood ( Figure 6A; data not shown). Thus, we examined the rate of accumulation of rhodopsin in wild-type animals and in animals expressing different amounts of NinaA. Drosophila rhodopsin is very stable, with a half-life of >48 h (Schwemer, 1984). Therefore, the levels of mature opsin detected by Western blots are a reliable indicator of its biosynthesis and maturation rates.…”

Section: Resultsmentioning

confidence: 99%

The cyclophilin homolog NinaA functions as a chaperone, forming a stable complex in vivo with its protein target rhodopsin.

1994

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Section: Resultsmentioning

confidence: 99%

The cyclophilin homolog NinaA functions as a chaperone, forming a stable complex in vivo with its protein target rhodopsin.

1994

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“…Drosophila phototransduction is a prototypic G protein-coupled receptor-signaling cascade (22)(23)(24). Like other G protein signaling cascades, invertebrate rhodopsin undergoes light-dependent turnover (16,25,26). In the blowfly, it has been demonstrated that rhodopsin has an extended half-life in flies maintained in the dark, whereas in flies maintained in light it has a short half-life (26).…”

Section: Ceramidase Facilitates Turnover Of Rh1 a Major Component Ofmentioning

confidence: 99%

“…Like other G protein signaling cascades, invertebrate rhodopsin undergoes light-dependent turnover (16,25,26). In the blowfly, it has been demonstrated that rhodopsin has an extended half-life in flies maintained in the dark, whereas in flies maintained in light it has a short half-life (26). Although rhodopsins undergo photochemical interconversion, light-activated rhodopsins are eventually endocytosed and degraded (26)(27)(28)(29).…”

Section: Ceramidase Facilitates Turnover Of Rh1 a Major Component Ofmentioning

confidence: 99%

“…In the blowfly, it has been demonstrated that rhodopsin has an extended half-life in flies maintained in the dark, whereas in flies maintained in light it has a short half-life (26). Although rhodopsins undergo photochemical interconversion, light-activated rhodopsins are eventually endocytosed and degraded (26)(27)(28)(29). In Drosophila, visual arrestins act as clathrin adaptors and have been demonstrated to bind and internalize light-activated Rh1 (28).…”

Section: Ceramidase Facilitates Turnover Of Rh1 a Major Component Ofmentioning

confidence: 99%

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Ceramidase expression facilitates membrane turnover and endocytosis of rhodopsin in photoreceptors

Acharya

Mowen²,

Nagashima³

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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Transgenic expression of ceramidase suppresses retinal degeneration in Drosophila arrestin and phospholipase C mutants. Here, we show that expression of ceramidase facilitates the dissolution of incompletely formed and inappropriately located elements of rhabdomeric membranes in ninaE I17 mutants lacking the G protein receptor Rh1 in R1-R6 photoreceptor cells. Ceramidase expression facilitates the endocytic turnover of Rh1. Although ceramidase expression aids the removal of internalized rhodopsin, it does not affect the turnover of Rh1 in photoreceptors maintained in dark, where Rh1 is not activated and thus has a slower turnover and a long half-life. Therefore, the phenotypic consequence of ceramidase expression in photoreceptors is caused by facilitation of endocytosis. This study provides mechanistic insight into the sphingolipid biosynthetic pathway-mediated modulation of endocytosis and suppression of retinal degeneration.S phingolipids are integral components of eukaryotic cell membranes. They are essential for survival of yeast, Drosophila, and mammals. Sphingolipids have a hydrophobic backbone moiety, ceramide, linked to a variable polar head group, e.g., phosphorylcholine in sphingomyelin and a saccharide in glycosphingolipids. Ceramide itself consists of a long chain base linked to a fatty acid. Ceramide, sphingosine, and sphingosine-1-P are lipid second messengers modulating a variety of cellular functions (1-3). Ceramide is at the branch point of the sphingolipid biosynthetic pathway and serves as a substrate for several enzymes, e.g., sphingomyelin synthase, ceramidase, ceramide kinase, and glucosylceramide synthase. In Drosophila, transgenic expression of a neutral ceramidase is accompanied by a decrease in the levels of ceramide (4). We have shown that modulation of enzymes of the sphingolipid biosynthetic pathway suppressed retinal degeneration in certain phototransduction mutants (4). Transgenic expression of ceramidase or a loss of one copy of the rate-limiting enzyme in the sphingolipid biosynthetic pathway, namely, Serine Palmitoyl CoA transferase, suppressed retinal degeneration in arrestin and phospholipase C (norpA) mutants. These backgrounds also suppressed degeneration in a dynamin mutant, suggesting that ceramidase was modulating the endocytic pathway. To gain further insight into the mechanism of ceramidase action, we have investigated the effects of ceramidase expression in the rhodopsin null mutant, ninaE I17 . Rhodopsin, the G protein-coupled receptor, transduces light signal in Drosophila photoreceptors R1-R6 (5, 6). Rhodopsin is also involved in the formation of a rhabdomere terminal web (RTW), an actin-based cytoskeletal scaffold implicated in rhabdomere biogenesis (7,8). Rhabdomeres are densely organized, specialized areas of plasma membrane that house the signal transduction machinery of photoreceptors. In ninaE I17 mutants, the RTW is not organized during morphogenesis and thus photoreceptors have improperly formed rhabdomeres (8). In addition, in 3-dayold flies, rhabdomeric e...

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“…The kinetics of the dark conversions of butterfly visual pigments is fast compared to that of fly visual pigment, where the time constant for metarhodopsin removal is 3.3 h and that of rhodopsin regeneration 200 h (blowfly; Schwemer 1984). Why are the processes in the fly so much slower?…”

Section: Butterfly Visual Pigments In Natural Conditionsmentioning

confidence: 99%

Visual pigment spectra of the comma butterfly, Polygonia c-album, derived from in vivo epi-illumination microspectrophotometry

Vanhoutte

Stavenga

2005

J Comp Physiol A

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Visual pigment spectra of the comma butterfly, Polygonia c-album, derived from in vivo epiillumination nation microspectrophotometry Vanhoutte, KJA; Stavenga, DG Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract The visual pigments in the compound eye of the comma butterfly, Polygonia c-album, were investigated in a specially designed epi-illumination microspectrophotometer. Absorption changes due to photochemical conversions of the visual pigments, or due to lightindependent visual pigment decay and regeneration, were studied by measuring the eye shine, i.e., the light reflected from the tapetum located in each ommatidium proximal to the visual pigment-bearing rhabdom. The obtained absorbance difference spectra demonstrated the dominant presence of a green visual pigment. The rhodopsin and its metarhodopsin have absorption peak wavelengths at 532 nm and 492 nm, respectively. The metarhodopsin is removed from the rhabdom with a time constant of 15 min and the rhodopsin is regenerated with a time constant of 59 min (room temperature). A UV rhodopsin with metarhodopsin absorbing maximally at 467 nm was revealed, and evidence for a blue rhodopsin was obtained indirectly.

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Renewal of visual pigment in photoreceptors of the blowfly

Cited by 76 publications

References 40 publications

The cyclophilin homolog NinaA functions as a chaperone, forming a stable complex in vivo with its protein target rhodopsin.

The cyclophilin homolog NinaA functions as a chaperone, forming a stable complex in vivo with its protein target rhodopsin.

Ceramidase expression facilitates membrane turnover and endocytosis of rhodopsin in photoreceptors

Visual pigment spectra of the comma butterfly, Polygonia c-album, derived from in vivo epi-illumination microspectrophotometry

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