Nir I, Cohen D, Papermaster D S
J Cell Biol. 1984 May;98(5):1788-95. doi: 10.1083/jcb.98.5.1788.
Mature retinal rod photoreceptors sequester opsin in the disk and plasma membranes of the rod outer segment (ROS). Opsin is synthesized in the inner segment and is transferred to the outer segment along the connecting cilium that joins the two compartments. We have investigated early stages of retinal development during which the polarized distribution of opsin is established in the rod photoreceptor cell. Retinas were isolated from newborn rats, 3-21 d old, and incubated with affinity purified biotinyl-sheep anti-bovine opsin followed by avidin-ferritin. At early postnatal ages prior to the development of the ROS, opsin is labeled by antiopsin on the inner segment plasma membrane. At the fifth postnatal day, as ROS formation begins opsin was detected on the connecting cilium plasma membrane. However, the labeling density of the ciliary plasma membrane was not uniform: the proximal cilium was relatively unlabeled in comparison with the distal cilium and the ROS plasma membrane. In nearly mature rat retinas, opsin was no longer detected on the inner segment plasma membrane. A similar polarized distribution of opsin was also observed in adult human rod photoreceptor cells labeled with the same antibodies. These results suggest that some component(s) of the connecting cilium and its plasma membrane may participate in establishing and maintaining the polarized distribution of opsin.
成熟的视网膜视杆光感受器将视蛋白隔离在视杆外段（ROS）的盘膜和质膜中。视蛋白在内段合成，并沿着连接两个部分的连接纤毛转移到外段。我们研究了视网膜发育的早期阶段，在此期间视蛋白在视杆光感受器细胞中建立了极化分布。从3至21日龄的新生大鼠中分离视网膜，并用亲和纯化的生物素化羊抗牛视蛋白孵育，然后用抗生物素蛋白-铁蛋白孵育。在ROS发育之前的出生后早期，视蛋白在内段质膜上被抗视蛋白标记。在出生后第5天，随着ROS形成开始，在连接纤毛质膜上检测到视蛋白。然而，睫状质膜的标记密度并不均匀：与远端纤毛和ROS质膜相比，近端纤毛相对未被标记。在几乎成熟的大鼠视网膜中，在内段质膜上不再检测到视蛋白。在用相同抗体标记的成人视杆光感受器细胞中也观察到视蛋白的类似极化分布。这些结果表明，连接纤毛及其质膜的某些成分可能参与建立和维持视蛋白的极化分布。
