Light-dependent subcellular translocation of Gqα in <i>Drosophila</i> photoreceptors is facilitated by the photoreceptor-specific myosin III NINAC

Cronin, Michelle; Diao, Feiyang; Tsunoda, Susan

doi:10.1242/jcs.01371

Cited by 54 publications

(78 citation statements)

References 63 publications

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“…As expected, the light-dependent shuttling of the Drosophila Gα q is dependent on rhodopsin; however, it does not require other known signaling proteins, such as NORPA [118,183], Arr2, PKC, TRP, and TRPL [183]. Thus, there may be other signaling proteins that remain to be identified, which interact with rhodopsin and promote the movement of the Gα q .…”

Section: Long-term Adaptation Through Light-dependent Translocation Osupporting

confidence: 62%

“…Consistent with this proposal, NINAC is required for translocation of the Gα q and Arr2 from the cell bodies to the rhabdomeres, but not for the movement out of the rhabdomeres [183,189]. However, trafficking of TRPL-eGFP out of the rhabdomeres is reported to be disrupted in the ninaC null mutant [188].…”

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 59%

“…In the dark, most of the Gα q is in the rhabdomeres, and then it moves to the cell bodies in the light over the course of a few minutes (Fig. 7a) [118,183]. In the dark, the Gα q subsequently returns to the membrane as an inactive GDP form.…”

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 99%

“…The basis for this latter observation is unclear but could be due to a variety of differences in the experimental protocols, which remain to be resolved. Nevertheless, the translocation of the Gα q from the cell bodies to the rhabdomeres is also dependent on NINAC [183]. In the case of the Gα q , this movement takes place in the dark.…”

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 99%

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Phototransduction and retinal degeneration in Drosophila

Wang

Montell

2007

Pflugers Arch - Eur J Physiol

261

303

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Drosophila visual transduction is the fastest known G-protein-coupled signaling cascade and has therefore served as a genetically tractable animal model for characterizing rapid responses to sensory stimulation. Mutations in over 30 genes have been identified, which affect activation, adaptation, or termination of the photoresponse. Based on analyses of these genes, a model for phototransduction has emerged, which involves phosphoinoside signaling and culminates with opening of the TRP and TRPL cation channels. Many of the proteins that function in phototransduction are coupled to the PDZ containing scaffold protein INAD and form a supramolecular signaling complex, the signalplex. Arrestin, TRPL, and Gα q undergo dynamic light-dependent trafficking, and these movements function in long-term adaptation. Other proteins play important roles either in the formation or maturation of rhodopsin, or in regeneration of phosphatidylinositol 4,5-bisphosphate (PIP 2 ), which is required for the photoresponse. Mutation of nearly any gene that functions in the photoresponse results in retinal degeneration. The underlying bases of photoreceptor cell death are diverse and involve mechanisms such as excessive endocytosis of rhodopsin due to stable rhodopsin/arrestin complexes and abnormally low or high levels of Ca 2+ . Drosophila visual transduction appears to have particular relevance to the cascade in the intrinsically photosensitive retinal ganglion cells in mammals, as the photoresponse in these latter cells appears to operate through a remarkably similar mechanism.

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Section: Long-term Adaptation Through Light-dependent Translocation Osupporting

confidence: 62%

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 59%

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 99%

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 99%

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Phototransduction and retinal degeneration in Drosophila

Wang

Montell

2007

Pflugers Arch - Eur J Physiol

261

303

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“…G-proteins mediate phototransduction signaling. Recent studies have revealed that transducin and G q translocate between the signaling compartments, and this plays a role in an adaptation mechanism (12)(13)(14). The other is visual arrestin that is responsible for termination of the photoresponse.…”

mentioning

confidence: 99%

Human Myosin III Is a Motor Having an Extremely High Affinity for Actin

Kambara

Komaba

Ikebe

2006

Journal of Biological Chemistry

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Myosin IIIA is expressed in photoreceptor cells and thought to play a critical role in phototransduction processes, yet its function on a molecular basis is largely unknown. Here we clarified the kinetic mechanism of the ATPase cycle of human myosin IIIA. The steady-state ATPase activity was markedly activated ϳ10-fold with very low actin concentration. The rate of ADP off from actomyosin IIIA was 10 times greater than the overall cycling rate, thus not a rate-determining step. The rate constant of the ATP hydrolysis step of the actin-dissociated form was very slow, but the rate was markedly accelerated by actin binding. The dissociation constant of the ATP-bound form of myosin IIIA from actin is submicromolar, which agrees well with the low K actin . These results indicate that ATP hydrolysis predominantly takes place in the actin-bound form for actomyosin IIIA ATPase reaction. The obtained K actin was much lower than the previously reported one, and we found that the autophosphorylation of myosin IIIA dramatically increased the K actin , whereas the V max was unchanged. Our kinetic model indicates that both the actin-attached hydrolysis and the P i release steps determine the overall cycle rate of the dephosphorylated form. Although the stable steady-state intermediates of actomyosin IIIA ATPase reaction are not typical strong actin-binding intermediates, the affinity of the stable intermediates for actin is much higher than conventional weak actin binding forms. The present results suggest that myosin IIIA can spend a majority of its ATP hydrolysis cycling time on actin.Class III myosin was originally found in Drosophila photoreceptor cells (1), and a majority of the cell biological work related to class III myosin has been done with the Drosophila system. Class III myosin was subsequently identified from humans (2, 3), striped bass (4), and Limulus (5). In vertebrate, two isoforms of class III myosin, myosin IIIA and myosin IIIB, have been cloned (2, 3). Among them, most studies have been done with myosin IIIA. Both isoforms are highly expressed in the retina. Myosin IIIA is also expressed in inner ear hair cells, and it is responsible for progressive nonsyndromic hearing loss in humans (6). Immunohistochemical studies revealed that myosin IIIA is concentrated in the distal ends of rod and cone ellipsoid and colocalizes with the plus-distal ends of inner segment actin filament bundles, where actin forms the microvilli-like calycal processes (4). Interestingly, the transfection of green fluorescent protein-myosin IIIA into HeLa cells revealed that myosin IIIA localizes at the tip of filopodia (7), suggesting that myosin IIIA accumulates at the plus end of actin bundles. The major cytoskeletal structure of filopodia is the actin bundles, and the plus ends of the actin filaments are localized at the tip; therefore, the localization of myosin IIIA at the tip of filopodia suggests that this myosin traveled on actin filaments and accumulated at the end of the actin track. This is consistent with our result that my...

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Mechanism of light‐induced translocation of arrestin and transducin in photoreceptors: Interaction‐restricted diffusion

Slepak

Hurley

2007

IUBMB Life

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SummaryMany signaling proteins change their location within cells in response to external stimuli. In photoreceptors, this phenomenon is remarkably robust. The G protein of rod photoreceptors and rod transducin concentrates in the outer segments (OS) of these neurons in darkness. Within 30 minutes after illumination, rod transducin redistributes throughout all of the outer and inner compartments of the cell. Visual arrestin concurrently relocalises from the inner compartments to become sequestered primarily within the OS. In the past several years, the question of whether these proteins are actively moved by molecular motors or whether they are redistributed by simple diffusion has been extensively debated. This review focuses on the most essential works in the area and concludes that the basic principle driving this protein movement is diffusion. The directionality and light dependence of this movement is achieved by the interactions of arrestin and transducin with their spatially restricted binding partners.

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Light-dependent subcellular translocation of Gqα in Drosophila photoreceptors is facilitated by the photoreceptor-specific myosin III NINAC

Cited by 54 publications

References 63 publications

Phototransduction and retinal degeneration in Drosophila

Phototransduction and retinal degeneration in Drosophila

Human Myosin III Is a Motor Having an Extremely High Affinity for Actin

Mechanism of light‐induced translocation of arrestin and transducin in photoreceptors: Interaction‐restricted diffusion

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