Kawamura S, Yokoyama S
Department of Biology, Syracuse University, NY 13244, USA.
Vision Res. 1998 Jan;38(1):37-44. doi: 10.1016/s0042-6989(97)00160-0.
Using only 11-cis 3, 4-dehydroretinal as a chromophore in the pure-cone retina, American chameleon (Anolis carolinensis) detects a wide range of color from ultraviolet (UV) to infrared. We previously characterized its visual opsin genes sws1Ac, sws2Ac, rh1Ac, rh2Ac, and LwsAc that encode SWS1Ac, SWS2Ac, RH1Ac, RH2Ac, and LWSAc opsins, respectively, and the pineal gland-specific opsin (PAc) gene. Here we present the light absorption profiles of the visual pigments obtained by expressing these opsins and reconstituting them with 11-cis retinal using the COS1 cell cDNA expression system. The purified SWS1Ac, SWS2Ac, RH1Ac, RH2Ac, LWSAc, and PAc pigments have the wavelengths of maximal absorption at 358, 437, 491, 495, 560, and 482 nm, respectively. SWS1Ac is the first vertebrate UV opsin whose spectral sensitivity has been directly evaluated. RH1 pigments, orthologous to the rod pigments of other vertebrates, are sensitive to hydroxylamine in the dark, exhibiting a cone pigment-like characteristic, probably reflecting their adaptation to the pure cone retina. Interestingly, the blue-sensitive SWS2Ac pigment shows an exceptionally low level of sensitivity to hydroxylamine, possessing a rod pigment-like characteristic.
在纯视锥视网膜中仅使用11-顺式3,4-脱氢视黄醛作为发色团，美国变色龙（安乐蜥）能检测从紫外线（UV）到红外线的广泛颜色范围。我们之前鉴定了其视觉视蛋白基因sws1Ac、sws2Ac、rh1Ac、rh2Ac和LwsAc，它们分别编码SWS1Ac、SWS2Ac、RH1Ac、RH2Ac和LWSAc视蛋白，以及松果体特异性视蛋白（PAc）基因。在此，我们展示了通过使用COS1细胞cDNA表达系统表达这些视蛋白并用11-顺式视黄醛重构它们而获得的视觉色素的光吸收谱。纯化后的SWS1Ac、SWS2Ac、RH1Ac、RH2Ac、LWSAc和PAc色素的最大吸收波长分别为358、437、491、495、560和482纳米。SWS1Ac是首个其光谱敏感性得到直接评估的脊椎动物紫外线视蛋白。与其他脊椎动物的视杆色素直系同源的RH1色素在黑暗中对羟胺敏感，表现出视锥色素样特征，这可能反映了它们对纯视锥视网膜的适应性。有趣的是，对蓝光敏感的SWS2Ac色素对羟胺的敏感性极低，具有视杆色素样特征。
