mRNA decay is a key step in regulating the cellular proteome. Processing bodies (P-bodies) are thought to be sites of mRNA decay and/or storage. P-body units assemble into P-body granules under stress conditions. How this assembly is regulated, however, remains poorly understood. Here, we show, in the yeast Saccharomyces cerevisiae, that the translational repressor Scd6 and the decapping stimulator Edc3 act partially redundantly in P-body assembly by sequestering the Dcp1-Dcp2 (denoted Dcp1/2) decapping complex in the cytoplasm and preventing it from becoming imported into the nucleus by the karyopherin β protein Kap95. One of two nuclear localization signals in Dcp2 overlaps with the RNA-binding site, suggesting an additional mechanism to regulate Dcp1/2 localization. Nuclear Dcp1/2 does not drive mRNA decay and might be stored there as a readily releasable pool, indicating a dynamic equilibrium between cytoplasmic and nuclear Dcp1/2. Cytoplasmic Dcp1/2 is linked to Dhh1 via Edc3. Functional P-bodies are present at the endoplasmic reticulum where Dcp2 potentially acts to increase the local concentration of Dhh1 through interaction with Edc3 to drive phase separation and hence P-body formation.

中文翻译：

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mRNA 脱帽复合物由核定位缓冲。

mRNA 衰变是调节细胞蛋白质组的关键步骤。加工体（P 体）被认为是 mRNA 衰变和/或储存的场所。P 体单元在应力条件下组装成 P 体颗粒。然而，如何调节这种组装仍然知之甚少。在这里，我们表明，在酵母酿酒酵母中，翻译抑制因子 Scd6 和脱帽刺激剂 Edc3 通过隔离细胞质中的 Dcp1-Dcp2（表示为 Dcp1/2）脱帽复合物并防止其在 P 体组装中部分冗余地起作用由 karyopherin β 蛋白 Kap95 输入细胞核。Dcp2 中的两个核定位信号之一与 RNA 结合位点重叠，表明存在调节 Dcp1/2 定位的额外机制。核 Dcp1/2 不会驱动 mRNA 衰变，并且可能作为易于释放的池储存在那里，表明细胞质和核 Dcp1/2 之间的动态平衡。细胞质 Dcp1/2 通过 Edc3 连接到 Dhh1。功能性 P 体存在于内质网中，其中 Dcp2 可能通过与 Edc3 相互作用来增加 Dhh1 的局部浓度，从而驱动相分离，从而形成 P 体。