英语翻译Species from multiple branches of theanimal kingdom have

英语翻译
Species from multiple branches of theanimal kingdom have evolved mechanisms to sense electromagnetic radiation intheir environments.Likewise many microbes,in the absence of complex eyestructures employed by metazoans,have developed light-activated proteins for avariety of purposes.For some,this serves as amechanism of homeostasis toremain at a certain depth in the ocean (Beja et al.2000,2001); for others,this helps maintain osmotic balance in a highly saline environment (Stoeckenius1985).These and other diverse roles are,in many cases,fulfilled by a family ofseven-transmembrane,light-responsive proteins encoded by opsin genes.
Opsingenes are divided into two distinct superfamilies:microbial opsins (type I)and animal opsins (type II).Opsin proteins from both families require retinal,a vitamin A–related organic cofactor that serves as the antenna for photons;when retinal is bound,the functional opsin proteins are termed rhodopsins.Retinal covalently attaches to a conserved lysine residue of helix 7 by forminga protonated retinal Schiff base (RSBH+).The ionic environment of the RSB,defined by the residues of the binding pocket,dictates the spectral andkinetic characteristics of each individual protein.Upon absorption of aphoton,retinal isomerizes and triggers a sequence of conformational changeswithin the opsin partner.The photoisomerized retinal is the triggerforsubsequentstructural rearrangements andactivities performed by these proteins.

动物王国中许多分支的物种都已进化出感知环境中电磁辐射的机制.与此相仿,许多缺乏多细胞动物的复杂眼睛结构的微生物业已发展出有多种用途的光激活蛋白.对于一些微生物来说,这是一种能在特定深度的海洋中停留的稳态机制（贝雅等,2000,2001年）,对于其他微生物来说,这有助于保持在高盐环境中维持渗透压平衡（Stoeckenius,1985）.在许多情况下,这些和其他各种功能是由视蛋白基因编码的七次跨膜、光反应型蛋白质家族所完成的.
视蛋白基因被分成两个不同的超级族群：微生物视蛋白（I型）和动物视蛋白（II型）.这两个族群的视蛋白都需要视黄醛,它是一种与维生素A相关的有机辅助因子,能作为光子的天线；当视黄醛被结合时,这种功能化的视蛋白被称为视紫红质.视黄醛通过形成视黄醛质子化Schiff碱(RSBH+)与保守的赖氨酸残基的第7个螺旋区共价相连.由结合区域的残基所确定的RSB离子环境,掌控着每个独立的蛋白质的光谱和动力学特征.在吸收一个光子后,视黄醛出现异构并触发与其结合的视蛋白的一系列构象变化.光异构的视黄醛是引发这些蛋白的后续结构重排和活动的原因.