BACKGROUND Correct chromosome segregation depends on the sister chromatid cohesion complex. The essential, evolutionarily conserved regulatory protein Irr1/Scc3, is responsible for the complex loading onto DNA and for its removal. We found that, unexpectedly, Irr1 is present not only in the nucleus but also in the cytoplasm. RESULTS We show that Irr1 protein is enriched in the cytoplasm upon arrest of yeast cells in G1 phase following nitrogen starvation, diauxic shift or α-factor action, and also during normal cell cycle. Despite the presence of numerous Crm1-dependent export signals, the cytoplasmic pool of Irr1 is not derived through export from the nucleus but instead is simply retained in the cytoplasm. Cytoplasmic Irr1 interacts with the Imi1 protein implicated in glutathione homeostasis and mitochondrial integrity. CONCLUSIONS Besides regulation of the sister chromatid cohesion complex in the nucleus Irr1 appears to have an additional role in the cytoplasm, possibly through interaction with the cytoplasmic protein Imi1.

中文翻译：

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Irr1 / Scc3蛋白与酿酒酵母中的染色体分离有关，具有双重核质定位。

背景技术正确的染色体分离取决于姐妹染色单体凝聚复合物。必需的，进化上保守的调节蛋白Irr1 / Scc3负责将复杂的蛋白质装载到DNA上并将其清除。我们发现，出乎意料的是，Irr1不仅存在于细胞核中，而且还存在于细胞质中。结果我们显示，在氮饥饿，双峰迁移或α因子作用后以及在正常细胞周期中，G1期酵母细胞停滞后，Irr1蛋白在细胞质中富集。尽管存在大量依赖Crm1的输出信号，但Irr1的细胞质库不是通过细胞核的输出而导出，而是仅保留在细胞质中。细胞质Irr1与涉及谷胱甘肽稳态和线粒体完整性的Imi1蛋白相互作用。