Wolfrum U
Zoologisches Institut I, Universität Karlsruhe (TH), Federal Republic of Germany.
Cell Motil Cytoskeleton. 1995;32(1):55-64. doi: 10.1002/cm.970320107.
Photoreceptor cells of vertebrate retinae are highly specialized ciliary cells. Their non-motile ciliated structure is restricted to the so-called connecting cilium at the joint between the light sensitive outer segment and the metabolically active inner segment. Extensive bidirectional intracellular transport between both segments is forced to occur through this tight connecting cilium. In the present study it is shown that the CA2+-binding, phospho-protein centrin is present in mammalian retinae. Western blot and immunoprecipitation reveal that anti-centrin antibodies react with purified photoreceptor cell fractions of retinae in bands at a molecular weight of 20 kDa, the molecular weight of centrins found in other cells. Indirect immunofluorescence analysis of cryosections through retinae of different mammalian species show that centrin is present only in centrosomes and basal bodies but also more extensively at the linkage between the inner and the outer segment of the photoreceptor cells. Immunocytological studies on isolated rod cells and immunoelectron microscopy clearly demonstrate a unique presence of centrin in the connecting cilium of photoreceptor cells. High molecular identity between centrins in lower eukaryotes and mammals indicates that centrin may play a role in cellular motility and/or in microtubule severing in the mammalian retina.
脊椎动物视网膜的光感受器细胞是高度特化的纤毛细胞。它们的非运动性纤毛结构局限于感光外段和代谢活跃的内段之间连接处的所谓连接纤毛。两个段之间广泛的双向细胞内运输被迫通过这个紧密的连接纤毛进行。在本研究中表明，结合钙的磷蛋白中心体蛋白存在于哺乳动物视网膜中。蛋白质免疫印迹和免疫沉淀显示，抗中心体蛋白抗体与视网膜纯化的光感受器细胞组分在分子量为20 kDa处有反应带，这是在其他细胞中发现的中心体蛋白的分子量。对不同哺乳动物物种视网膜冰冻切片的间接免疫荧光分析表明，中心体蛋白不仅存在于中心体和基体中，而且在光感受器细胞内段和外段之间的连接处也更广泛地存在。对分离的视杆细胞的免疫细胞学研究和免疫电子显微镜清楚地证明了中心体蛋白在光感受器细胞连接纤毛中的独特存在。低等真核生物和哺乳动物的中心体蛋白之间的高分子同一性表明，中心体蛋白可能在哺乳动物视网膜的细胞运动和/或微管切断中起作用。
