Cooper N, Liu L, Yoshida A, Pozdnyakov N, Margulis A, Sitaramayya A
Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, KY, USA.
J Mol Neurosci. 1995;6(3):211-22. doi: 10.1007/BF02736766.
Cyclic-GMP, which plays a pivotal role in visual transduction in the vertebrate retina, is synthesized by guanylate cyclase. The purpose of this study was to localize a rod outer segment-derived particulate guanylate cyclase (ROS-GC) to the retina of several species that have different populations of rods and cones. A rabbit antibody was raised against a synthetic peptide, corresponding to the sequence A107-L125 of bovine ROS-GC. Western blot analysis showed a single immunoreactive band at about 115 kDa with bovine rod outer segments but not with human rod outer segments. Light microscopic immunocytochemistry of tissue sections revealed immunoreactivity in the outer segment layer and in the outer and inner plexiform layers. The rod-rich rat retina showed uniform immunolabeling of outer segments; the cone-containing cat retina showed heavily labeled cone outer segments and lighter labeling of rod outer segments; the cone-rich chicken retina showed a uniformly and intensely labeled outer segment layer. Preincubation of the primary antibody with the peptide completely blocked antibody binding. Electron microscopic immunocytochemistry of the cat retina confirmed the presence of guanylate cyclase in photoreceptor outer segments and demonstrated its association with disk and plasma membranes. These data support a concept in which guanylate cyclase is much more concentrated in the outer segments of cones than rods. The immunolabeling of the plexiform layers suggests that the particulate guanylate cyclase is not unique to the photoreceptor outer segments, and may also play a role in transduction processes of retinal synapses.
环磷酸鸟苷（Cyclic-GMP）在脊椎动物视网膜的视觉转导中起关键作用，它由鸟苷酸环化酶合成。本研究的目的是将一种来源于视杆细胞外段的颗粒性鸟苷酸环化酶（ROS-GC）定位到几种具有不同视杆细胞和视锥细胞群体的物种的视网膜中。制备了一种兔抗体，该抗体针对与牛ROS-GC的A107-L125序列相对应的合成肽。蛋白质印迹分析显示，牛视杆细胞外段在约115 kDa处有一条单一的免疫反应条带，而人视杆细胞外段则没有。组织切片的光学显微镜免疫细胞化学显示在外段层以及外网状层和内网状层有免疫反应性。视杆细胞丰富的大鼠视网膜在外段显示出均匀的免疫标记；含有视锥细胞的猫视网膜显示视锥细胞外段标记强烈，视杆细胞外段标记较弱；视锥细胞丰富的鸡视网膜在外段层显示出均匀且强烈的标记。用该肽预孵育一抗可完全阻断抗体结合。猫视网膜的电子显微镜免疫细胞化学证实了光感受器外段中存在鸟苷酸环化酶，并证明其与盘膜和质膜相关。这些数据支持了一个概念，即鸟苷酸环化酶在视锥细胞外段中的浓度比视杆细胞外段高得多。网状层的免疫标记表明颗粒性鸟苷酸环化酶并非光感受器外段所特有，可能在视网膜突触的转导过程中也起作用。
