Brain cytoplasmic and flagellar outer arm dyneins share a highly conserved M(r) 8,000 light chain
Brain cytoplasmic and flagellar outer arm dyneins share a highly conserved M(r) 8,000 light chain
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DOI：
10.1074/jbc.271.32.19358
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发表时间：
1996-08-09
影响因子：
4.8
通讯作者：
Pfister, KK
中科院分区：
文献类型：
--
作者：
King, SM;Barbarese, E;Pfister, KK
与来自衣原体外臂动力蛋白的M（r）8，000轻链的序列比较揭示了在表达的序列标签数据库中存在高度保守的同源物（高达90%同一性）（King，S. M. & Patel-King，R. S.（1995 a）J. Biol. Chem. 270，11445-11452）。这些同源序列中的几个来源于缺乏运动纤毛/鞭毛的生物体和/或组织，表明这些蛋白质可能在细胞质中起作用。在果蝇中，同源蛋白质的缺乏导致胚胎致死（Dick，T.，Ray，K.，萨尔茨湾K. & Chia，W.等人（1996）Mol. Cell.生物学：16，1966-1977）。分级哺乳动物脑匀浆揭示了三个不同的同源蛋白质，其中之一，具体copurifies与细胞质动力蛋白后两个ATP敏感的微管亲和/蔗糖密度梯度离心和免疫沉淀的单克隆抗体特异性的74-kDa的中间链（IC 74）的胞浆池。定量光密度测定法表明每个IC 74有一个拷贝的M（r）8，000多肽。双通道共聚焦免疫荧光显微镜显示，M（r）8，000蛋白与细胞质动力蛋白显着共定位，但不与驱动蛋白在哺乳动物少突胶质细胞内的点状结构（其中许多与微管相关）。因此，看来，鞭毛外臂和脑细胞质动力蛋白共享一个高度保守的轻链多肽，至少在果蝇，是必不可少的生存能力。
Sequence comparisons with the M(r) 8,000 light chain from Chlamydomonas outer arm dynein revealed the presence of highly conserved homologues (up to 90% identity) in the expressed sequence tag data base (King, S. M. & Patel-King, R. S. (1995a) J. Biol. Chem. 270, 11445-11452). Several of these homologous sequences were derived from organisms and/or tissues that lack motile cilia/flagella, suggesting that these proteins may function in the cytoplasm. In Drosophila, lack of the homologous protein results in embryonic lethality (Dick, T., Ray, K., Salz, H. K. & Chia, W. (1996) Mol. Cell. Biol., 16, 1966-1977). Fractionation of mammalian brain homogenates reveals three distinct cytosolic pools of the homologous protein, one of which specifically copurifies with cytoplasmic dynein following both ATP-sensitive microtubule affinity/sucrose density gradient centrifugation and immunoprecipitation with a monoclonal antibody specific for the 74-kDa intermediate chain (IC74). Quantitative densitometry indicates that there is one copy of the M(r) 8,000 polypeptide per IC74. Dual channel confocal immunofluorescent microscopy revealed that the M(r) 8,000 protein is significantly colocalized with cytoplasmic dynein but not with kinesin in punctate structures (many of which are associated with microtubules) within mammalian oligodendrocytes. Thus, it appears that flagellar outer arm and brain cytoplasmic dyneins share a highly conserved light chain polypeptide that, at least in Drosophila, is essential for viability.