The membrane transport tartar p115 recycles only between homologous compartments in intact heterokaryons
The membrane transport tartar p115 recycles only between homologous compartments in intact heterokaryons
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DOI：
10.1078/s0171-9335(04)70026-6
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发表时间：
2000-04-01
影响因子：
6.6
通讯作者：
Sztul, ES
中科院分区：
文献类型：
--
作者：
García-Mata, R;Gao, YS;Sztul, ES
参与膜运输的胞质蛋白质被认为是从胞质中募集到特定的膜位点上，在那里它们执行它们的功能，然后在重新结合以催化另一轮运输之前释放到胞质中。为了检测ER到高尔基体转运因子p115是否通过释放到胞质池中而聚集，我们在大鼠NRK和猿COS-7细胞之间形成异核体，并检测大鼠p115从大鼠转移到异核体的猿部分的动力学。异核体共享一个共同的胞质池，如胞质绿色荧光蛋白（GFP）从COS-7到异核体NRK部分的有效重新定位所示。出乎意料的是，即使在细胞融合后24小时，大鼠p115没有重新分配到异核体的COS-7部分。这不是由于大鼠p115不能与猿猴膜结合，因为在COS-7细胞中表达的大鼠p115有效地靶向猿猴高尔基复合体并与之结合。此外，在NRK和COS-7 Golgi融合成单个嵌合结构后，大鼠p115与异源猿猴膜结合。我们的研究结果表明，p115在完整的细胞中不能自由扩散，并且可能在其整个生命周期中保持束缚在膜上。这些研究结果表明，p115，也许其他细胞质蛋白参与膜交通，回收被释放到细胞质，但与回收膜。
Cytosolic proteins that participate in membrane traffic are assumed to be recruited from the cytosol onto specific membrane sites where they perform their function, and then released into cytosol before rebinding to catalyze another round of transport. To examine whether the ER to Golgi transport factor p115 recycles through release into a cytosolic pool, we formed heterokaryons between rat NRK and simian COS-7 cells and examined the dynamics of rat p115 transfer from the rat to the simian portion of the heterokaryon, The heterokaryons shared a common cytosolic pool, as shown by the efficient relocation of a cytosolic green fluorescent protein (GFP) from the COS-7 to the NRK part of the heterokaryon. Unexpectedly, even 24 h after cell fusion, rat p115 did not redistribute to the COS-7 part of the heterokaryon. This was not due to the inability of the rat p115 to associate with simian membranes since rat p115 expressed in COS-7 cells was efficiently targeted to and associated with simian Golgi complex. Furthermore, rat p115 associated with heterologous simian membranes after the NRK and COS-7 Golgi fused into a single chimeric structure. Our results indicate that p115 is not freely diffusible in intact cells and might remain tethered to membranes throughout its life cycle. These findings suggest that p115, and perhaps other cytosolic proteins involved in membrane traffic, recycle not by being released into cytosol, but in association with recycling membranes.