We live on a planet that is bathed in daily and seasonal sunlight cycles. In this context, terrestrial life forms have evolved mechanisms that directly harness light energy (plants) or decode light information for adaptive advantage. In animals, the main light sensors are a family of G protein–coupled receptors called opsins. Opsin function is best described for the visual sense. However, most animals also use opsins for extraocular light sensing for seasonal behavior and camouflage. While it has long been believed that mammals do not have an extraocular light sensing capacity, recent evidence suggests otherwise. Notably, encephalopsin (OPN3) and neuropsin (OPN5) are both known to mediate extraocular light sensing in mice. Examples of this mediation include photoentrainment of circadian clocks in skin (by OPN5) and acute light-dependent regulation of metabolic pathways (by OPN3 and OPN5). This review summarizes current findings in the expanding field of extraocular photoreception and their relevance for human physiology.

中文翻译：

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非视觉视蛋白在眼外光传感生理学中的作用不断扩大

我们生活在一个每天和季节性阳光循环沐浴的星球上。在这种背景下，陆地生命形式已经进化出直接利用光能（植物）或解码光信息以获得适应性优势的机制。在动物中，主要的光传感器是称为视蛋白的 G 蛋白偶联受体家族。视蛋白功能最好用视觉来描述。然而，大多数动物也使用视蛋白进行眼外光感应，以实现季节性行为和伪装。虽然长期以来人们一直认为哺乳动物没有眼外光感应能力，但最近的证据表明事实并非如此。值得注意的是，已知脑紫质蛋白 (OPN3) 和神经蛋白酶 (OPN5) 均可介导小鼠的眼外光感应。这种调节的例子包括皮肤生物钟的光诱导（通过 OPN5）和代谢途径的急性光依赖性调节（通过 OPN3 和 OPN5）。这篇综述总结了眼外感光领域的最新发现及其与人类生理学的相关性。