This paper reviews current knowledge of the evolution of the multiple genes encoding proteins that mediate the process of phototransduction in rod and cone photoreceptors of vertebrates. The approach primarily involves molecular phylogenetic analysis of phototransduction protein sequences, combined with analysis of the syntenic arrangement of the genes. At least 35 of these phototransduction genes appear to reside on no more than five paralogons – paralogous regions that each arose from a common ancestral region. Furthermore, it appears that such paralogs arose through quadruplication during the two rounds of genome duplication (2R WGD) that occurred in a chordate ancestor prior to the vertebrate radiation, probably around 600 millions years ago. For several components of the phototransduction cascade, it is shown that distinct isoforms already existed prior to WGD, with the likely implication that separate classes of scotopic and photopic photoreceptor cells had already evolved by that stage. The subsequent quadruplication of the entire genome then permitted the refinement of multiple distinct protein isoforms in rods and cones. A unified picture of the likely pattern and approximate timing of all the important gene duplications is synthesised, and the implications for our understanding of the evolution of rod and cone phototransduction are presented.

本文综述了目前在编码蛋白的多个基因的进化方面的知识，这些蛋白介导脊椎动物的杆状和锥状光感受器的光转导过程。该方法主要涉及光转导蛋白序列的分子系统发育分析，以及对基因的序列安排的分析。这些光转导基因中至少有35个似乎驻留在不超过5个旁系同源物上-每个旁系同源区均起源于一个共同的祖先区。此外，似乎这种同源物是在大约六亿年前的脊椎动物辐射之前，在一个date酸盐祖先中发生的两轮基因组复制（2R WGD）过程中，通过四倍复制而产生的。对于光电转导级联的几个组成部分，结果表明，在WGD之前已经存在不同的同工型，这可能暗示着在这一阶段已经演化出了不同种类的暗视和可见光感受器细胞。整个基因组随后的四联体然后允许细化杆和视锥细胞中多种不同的蛋白质同工型。合成了所有重要基因重复的可能模式和近似时间的统一图片，并提出了对我们理解杆和锥光转导的进化的启示。