Molecular Mechanism of re-isomerization ofretinal in visual cycle

视色素对光子的吸收诱导11-顺式-视黄醛（RAL）发色团异构化为全反式-RAL。在这里，我们比较了脊椎动物和无脊椎动物的不同光感受器之间的视觉类维生素A循环。海鞘是脊椎动物的近亲，其视觉循环系统处于脊椎动物和非脊索动物之间的中间状态。海鞘幼虫可能利用视色素样视蛋白作为主要的视黄酸异构酶，但asidinan中的RPE 65不异构视黄酸。这些结果在进化观点上是非常有趣的。

Absorption of a photon by visual pigments induces isomerization of 11-cis-retinaldehyde(RAL) chromophore to all-trans-RAL. Here we comparevisual retinoid cycles between different photoreceptors of vertebrates as well as invertebrates. The visual cycle systems in ascidians, the closest living relatives of vertebrates, show an intermediate state between vertebrates and non-chordate invertebrates. The ascidian larva may use retinochrome-like opsin as the major isomerase retinal but RPE65 in asidinan did not isomerase retinal. These results are very interesting in the evolutional standpoints.