Herrmann C, Golkaramnay E, Inman E, Rome L, Volknandt W
Biozentrum der J. W. Goethe-Universität, D-60439 Frankfurt/Main, Germany.
J Cell Biol. 1999 Mar 22;144(6):1163-72. doi: 10.1083/jcb.144.6.1163.
The major vault protein (MVP) is the predominant constituent of ubiquitous, evolutionarily conserved large cytoplasmic ribonucleoprotein particles of unknown function. Vaults are multimeric protein complexes with several copies of an untranslated RNA. Double labeling employing laser-assisted confocal microscopy and indirect immunofluorescence demonstrates partial colocalization of vaults with cytoskeletal elements in Chinese hamster ovary (CHO) and nerve growth factor (NGF)-treated neuronlike PC12 cells. Transfection of CHO and PC12 cells with a cDNA encoding the rat major vault protein containing a vesicular stomatitis virus glycoprotein epitope tag demonstrates that the recombinant protein is sorted into vault particles and targeted like endogenous MVPs. In neuritic extensions of differentiated PC12 cells, there is an almost complete overlap of the distribution of microtubules and vaults. A pronounced colocalization of vaults with filamentous actin can be seen in the tips of neurites. Moreover, in NGF-treated PC12 cells the location of vaults partially coincides with vesicular markers. Within the terminal tips of neurites vaults are located near secretory organelles. Our observations suggest that the vault particles are transported along cytoskeletal-based cellular tracks.
主要穹窿蛋白（MVP）是普遍存在的、进化保守的大型细胞质核糖核蛋白颗粒的主要成分，其功能未知。穹窿是具有多个未翻译RNA拷贝的多聚体蛋白复合物。采用激光辅助共聚焦显微镜和间接免疫荧光的双重标记显示，在中国仓鼠卵巢（CHO）细胞和经神经生长因子（NGF）处理的类神经元PC12细胞中，穹窿与细胞骨架成分部分共定位。用编码含有水泡性口炎病毒糖蛋白表位标签的大鼠主要穹窿蛋白的cDNA转染CHO细胞和PC12细胞，结果表明重组蛋白被分选到穹窿颗粒中，并像内源性MVP一样被靶向运输。在分化的PC12细胞的神经突延伸中，微管和穹窿的分布几乎完全重叠。在神经突尖端可见穹窿与丝状肌动蛋白明显共定位。此外，在经NGF处理的PC12细胞中，穹窿的位置部分与囊泡标记物重合。在神经突的末端尖端，穹窿位于分泌细胞器附近。我们的观察结果表明，穹窿颗粒沿着基于细胞骨架的细胞轨道运输。
