Chaitin M H, Schneider B G, Hall M O, Papermaster D S
J Cell Biol. 1984 Jul;99(1 Pt 1):239-47. doi: 10.1083/jcb.99.1.239.
Actin has been localized in Rana pipiens retinas that were fixed and embedded in aldehyde cross-linked BSA. Thin sections were reacted sequentially with (a) affinity-purified antiactin antibodies induced in rabbits; (b) biotinyl-sheep anti-rabbit antibodies; and (c) avidin-ferritin conjugates. As expected, antiactin labeling density was high in the apical pigment epithelial cell processes and in the calycal processes of photoreceptors. Actin was also localized in a new site. The connecting cilium that joins the inner and outer segments of both rods and cones was heavily labeled by antiactin at its outer segment (OS), or distal, end. In this region of the cilium, the plasma membrane evaginates to form new OS disks and these basal disks were labeled in some instances. Below the new disks in rods, the cytoplasm of liplike expansions of the distal cilium was also heavily labeled. The plasma membrane and interior of the connecting cilium and the remainder of the OS were unlabeled. These findings suggest that actin may participate in the vectorial transport of opsin and other intrinsic membrane proteins that are incorporated into newly forming OS disks. The results also implicate actin in the membrane expansion involved with OS disk formation.
肌动蛋白已定位在固定并包埋于醛交联牛血清白蛋白中的豹蛙视网膜中。对薄片依次进行如下反应：(a) 用在兔体内诱导产生的亲和纯化抗肌动蛋白抗体；(b) 生物素化羊抗兔抗体；以及 (c) 抗生物素蛋白-铁蛋白缀合物。正如预期的那样，抗肌动蛋白标记密度在顶端色素上皮细胞突起和光感受器的杯状突起中较高。肌动蛋白也定位于一个新的部位。连接视杆和视锥细胞内、外节的连接纤毛在其外节（OS）或远端末端被抗肌动蛋白大量标记。在纤毛的这个区域，质膜内陷形成新的OS盘，并且在某些情况下这些基部盘也被标记。在视杆细胞中新盘下方，远端纤毛的唇状膨大的细胞质也被大量标记。连接纤毛的质膜和内部以及OS的其余部分未被标记。这些发现表明肌动蛋白可能参与视蛋白和其他整合到新形成的OS盘中的内在膜蛋白的定向运输。结果还表明肌动蛋白参与了与OS盘形成相关的膜扩张。
