Deguchi-Tawarada Maki, Inoue Eiji, Takao-Rikitsu Etsuko, Inoue Marie, Kitajima Isao, Ohtsuka Toshihisa, Takai Yoshimi
KAN Research Institute, Kyoto 600-8815, Japan.
J Comp Neurol. 2006 Apr 1;495(4):480-96. doi: 10.1002/cne.20893.
CAST is a novel cytomatrix at the active zone (CAZ)-associated protein. In conventional brain synapses, CAST forms a large molecular complex with other CAZ proteins, including RIM, Munc13-1, Bassoon, and Piccolo. Here we investigated the distribution of CAST and its structurally related protein, ELKS, in mouse retina. Immunofluorescence analyses revealed that CAST and ELKS showed punctate signals in the outer and inner plexiform layers of the retina that were well-colocalized with those of Bassoon and RIM. Both proteins were found presynaptically at glutamatergic ribbon synapses, and at conventional GABAergic and glycinergic synapses. Moreover, immunoelectron microscopy revealed that CAST, like Bassoon and RIM, localized at the base of synaptic ribbons, whereas ELKS localized around the ribbons. Both proteins also localized in the vicinity of the presynaptic plasma membrane of conventional synapses in the retina. These results indicated that CAST and ELKS were novel components of the presynaptic apparatus of mouse retina.
CAST是一种与活性区（CAZ）相关的新型细胞基质蛋白。在传统的脑突触中，CAST与其他CAZ蛋白形成大分子复合物，包括RIM、Munc13-1、巴松管蛋白和 piccolo。在这里，我们研究了CAST及其结构相关蛋白ELKS在小鼠视网膜中的分布。免疫荧光分析显示，CAST和ELKS在视网膜的外丛状层和内丛状层呈现点状信号，与巴松管蛋白和RIM的信号高度共定位。这两种蛋白在谷氨酸能带状突触以及传统的GABA能和甘氨酸能突触的突触前均有发现。此外，免疫电子显微镜显示，CAST与巴松管蛋白和RIM一样，定位于突触带的基部，而ELKS定位于突触带周围。这两种蛋白也定位于视网膜中传统突触的突触前质膜附近。这些结果表明，CAST和ELKS是小鼠视网膜突触前装置的新成分。
