Nasmyth K, Seddon A, Ammerer G
Cell. 1987 May 22;49(4):549-58. doi: 10.1016/0092-8674(87)90457-0.
In haploid homothallic yeast, cell division gives rise to a mother cell that transiently transcribes the HO gene (as it undergoes START) and a daughter cell that does not. Consequently, only mother cells switch their mating types. Here, we test the proposition that a transcription factor called SWI5 is the "determinant" of mother-cell-specific HO transcription; that is, that SWI5 is the only factor missing in daughter cells. We show that SWI5 RNAs are cell-cycle regulated so that they are only produced after the post-START window of HO transcription. This regulation is vital for mother-cell specificity since constitutive transcription of SWI5 causes daughter cells to switch their mating types. We propose that SWI5 gene products are partitioned asymmetrically at cell division.
在单倍体同宗配合酵母中，细胞分裂产生一个母细胞（在经历起始点时会短暂转录HO基因）和一个不转录HO基因的子细胞。因此，只有母细胞会转换其交配型。在这里，我们测试了一种观点，即一种名为SWI5的转录因子是母细胞特异性HO转录的“决定因素”；也就是说，SWI5是子细胞中唯一缺失的因子。我们发现SWI5 RNA受细胞周期调控，因此它们只在HO转录的起始点后窗口期产生。这种调控对于母细胞特异性至关重要，因为SWI5的组成型转录会导致子细胞转换其交配型。我们提出SWI5基因产物在细胞分裂时不对称分配。
