Smith W C, Price D A, Greenberg R M, Battelle B A
Whitney Marine Laboratory, University of Florida, Gainesville 32086.
Proc Natl Acad Sci U S A. 1993 Jul 1;90(13):6150-4. doi: 10.1073/pnas.90.13.6150.
cDNA clones encoding opsins from the lateral eyes and median ocelli of the horseshoe crab, Limulus polyphemus, were isolated from cDNA libraries. The opsin cDNAs obtained from the lateral eye and ocellar libraries code for deduced proteins with 376 amino acids. The two cDNAs are 96% identical at the nucleic acid level, differing primarily at the 3' untranslated region, and are apparently the products of two separate genes. The deduced opsin proteins are 99% identical to each other, differing at only 5 amino acids. The opsins encoded by these cDNAs are most likely the protein moiety of the visible-wavelength rhodopsins in this animal. In the lateral eye, expression of the opsin gene is restricted to the photoreceptor cells of the ommatidia. Comparisons with opsins of other species show that the Limulus opsin proteins are most similar (53% identity) to the opsin from the R1-6 photoreceptors of flies.
从马蹄蟹（美洲鲎）复眼和中单眼的互补DNA（cDNA）文库中分离出了编码视蛋白的cDNA克隆。从复眼文库和单眼文库中获得的视蛋白cDNA编码推导的含376个氨基酸的蛋白质。这两个cDNA在核酸水平上有96%的同一性，主要在3'非翻译区存在差异，显然是两个不同基因的产物。推导的视蛋白彼此有99%的同一性，仅在5个氨基酸上不同。这些cDNA编码的视蛋白很可能是该动物可见波长视紫红质的蛋白质部分。在复眼中，视蛋白基因的表达局限于小眼的光感受器细胞。与其他物种视蛋白的比较表明，美洲鲎视蛋白与果蝇R1 - 6光感受器的视蛋白最为相似（同一性为53%）。
