Ca2+-dependent metarhodopsin inactivation mediated by calmodulin and NINAC myosin III.
Ca2+-dependent metarhodopsin inactivation mediated by calmodulin and NINAC myosin III.
复制标题
Ca2+依赖性的元视丁蛋白失活由钙调蛋白和尼纳克肌球蛋白III介导。
DOI：
10.1016/j.neuron.2008.07.007
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发表时间：
2008-09-11
期刊：
影响因子：
16.2
通讯作者：
Hardie, Roger C.
中科院分区：
文献类型：
--
作者：
Liu, Che-Hsiung;Satoh, Akiko K.;Postma, Marten;Huang, Jiehong;Ready, Donald F.;Hardie, Roger C.
果蝇中的光转导是已知最快的G蛋白偶联信号级联，但这种性能是如何实现的仍不清楚。在这里，我们调查的机制和作用的视紫红质失活。我们确定的寿命激活视紫红质（metarhodopsin = M*）在全细胞记录从果蝇感光细胞通过测量的时间窗口内，通过photoreisomerization到视紫红质灭活M* 可以抑制响应先前的照明。M* 在对照条件下迅速失活（τ ~20 ms），但在无Ca 2+溶液中失活慢约10倍。这种明显的Ca 2+依赖性M* 失活不受影响的视紫红质或arrestin的磷酸化突变，但在钙调蛋白（CaM）或钙调蛋白结合肌球蛋白III，NINAC的突变体中被废除。这表明了一种新的机制，其中Ca 2+内流通过CaM和NINAC作用加速了arrestin与M* 的结合。我们的研究结果表明，这种策略促进量子效率，时间分辨率和保真度的视觉信号。
Phototransduction in flies is the fastest known G-protein coupled signalling cascade, but how this performance is achieved remains unclear. Here we investigate the mechanism and role of rhodopsin inactivation. We determined the lifetime of activated rhodopsin (metarhodopsin = M*) in whole-cell recordings from Drosophila photoreceptors by measuring the time window within which inactivating M* by photoreisomerization to rhodopsin could suppress responses to prior illumination. M* was inactivated rapidly (τ ~20 ms) under control conditions, but ~10-fold more slowly in Ca2+ free solutions. This pronounced Ca2+ dependence of M* inactivation was unaffected by mutations affecting phosphorylation of rhodopsin or arrestin, but was abolished in mutants of calmodulin (CaM) or the CaM binding myosin III, NINAC. This suggests a novel mechanism whereby Ca2+ influx acting via CaM and NINAC accelerates the binding of arrestin to M*. Our results indicate that this strategy promotes quantum efficiency, temporal resolution and fidelity of visual signalling.
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影响因子：
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