Nasmyth K, Adolf G, Lydall D, Seddon A
Research Institute of Molecular Pathology, Vienna, Austria.
Cell. 1990 Aug 24;62(4):631-47. doi: 10.1016/0092-8674(90)90110-z.
HO encodes a site-specific endonuclease that initiates mating type switching in S. cerevisiae. It is expressed only transiently during the cell cycle of mother cells, as they undergo Start, but not in daughter cells. Since SWI5 appears to be the only HO transcription factor missing when daughter cells undergo Start, we were interested in the intracellular distribution of SWI5 at cell division. We discovered that SWI5 is found equally concentrated in the nuclei of both mother and daughter cells at the end of anaphase, suggesting that its subsequent fate must somehow differ. Prior to the end of anaphase, SWI5 accumulates in the cytoplasm and only moves into the nucleus when cells enter G1. A version of the HO promoter that has lost its dependence on Start is nevertheless still strongly cell cycle regulated and is activated when SWI5 moves into the nucleus.
HO编码一种位点特异性内切核酸酶，该酶启动酿酒酵母中的交配型转换。它仅在母细胞的细胞周期中短暂表达，即在它们进入起始点时表达，但在子细胞中不表达。由于当子细胞进入起始点时，SWI5似乎是唯一缺失的HO转录因子，因此我们对细胞分裂时SWI5在细胞内的分布感兴趣。我们发现，在后期结束时，SWI5在母细胞和子细胞核中的浓度相同，这表明其随后的命运必定以某种方式有所不同。在后期结束之前，SWI5在细胞质中积累，只有当细胞进入G1期时才移入细胞核。尽管HO启动子的一个版本已失去对起始点的依赖性，但它仍然受到强烈的细胞周期调控，并且当SWI5移入细胞核时被激活。
