Okano T, Yoshizawa T, Fukada Y
Department of Pure and Applied Sciences, College of Arts and Sciences, University of Tokyo, Japan.
Nature. 1994 Nov 3;372(6501):94-7. doi: 10.1038/372094a0.
In avian pinealocytes, an environmental light signal resets the phase of the endogenous circadian pacemaker that controls the rhythmic production of melatonin. Investigation of the pineal phototransduction pathway should therefore reveal the molecular mechanism of the biological clock. The presence of rhodopsin-like photoreceptive pigment, transducin-like immunoreaction, and cyclic GMP-dependent cation-channel activity in the avian pinealocytes suggests that there is a similarity between retinal rod cells and pinealocytes in the phototransduction pathway. We have now cloned chicken pineal cDNA encoding the photoreceptive molecule, which is 43-48% identical in amino-acid sequence to vertebrate retinal opsins. Pineal opsin, produced by transfection of complementary DNA into cultured cells, was reconstituted with 11-cis-retinal, resulting in formation of a blue-sensitive pigment (lambda max approximately 470 nm). In the light of this functional evidence and because the gene is specifically expressed only in the pineal gland, we conclude that it is a pineal photosensor and name it pinopsin.
在禽类松果体细胞中，环境光信号会重置内源性昼夜节律起搏器的相位，该起搏器控制褪黑素的节律性分泌。因此，对松果体光转导途径的研究应能揭示生物钟的分子机制。禽类松果体细胞中存在视紫红质样光感受色素、转导蛋白样免疫反应以及环鸟苷酸依赖性阳离子通道活性，这表明视网膜视杆细胞与松果体细胞在光转导途径上存在相似性。我们现已克隆出编码光感受分子的鸡松果体互补脱氧核糖核酸（cDNA），其氨基酸序列与脊椎动物视网膜视蛋白有43%至48%的同源性。通过将互补DNA转染到培养细胞中产生的松果体视蛋白，与11-顺式视黄醛重组，形成了一种对蓝光敏感的色素（最大吸收波长约为470纳米）。鉴于这一功能证据，且由于该基因仅在松果体中特异性表达，我们得出结论，它是一种松果体光感受器，并将其命名为视锥蛋白。
