TRANSCRIPTION FACTORS IMPORTANT FOR STARTING THE CELL-CYCLE IN YEAST
TRANSCRIPTION FACTORS IMPORTANT FOR STARTING THE CELL-CYCLE IN YEAST
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DOI：
10.1098/rstb.1993.0078
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发表时间：
1993-06-29
期刊：
影响因子：
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通讯作者：
NASMYTH, K
中科院分区：
文献类型：
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作者：
MOLL, T;SCHWOB, E;NASMYTH, K
与某些动物的早期胚胎分裂不同，酵母中的细胞周期进展，可能也包括所有后生动物体细胞，都需要某些关键基因的周期性转录激活。到目前为止，唯一清楚的例子是编码一类不稳定的周期蛋白的基因，它结合并激活cdc2/cdc28蛋白激酶：由CLN1和CLN2编码的G1-特异性周期蛋白，CLB5编码的DNA复制涉及的一种B型周期蛋白；以及由CLB1、2、3、4编码的四个B型周期蛋白。随着细胞的启动，CLN1、CLN2和CLB5在G1晚期转录。由Swi4和Swi6蛋白组成的转录因子(称为SBF)通过CLN蛋白激活自身转录的正反馈环来激活CLN1和CLN2的转录。一种不同但相关的转录因子MBF似乎对包括CLB5在内的大多数DNA复制基因的G1晚期特异转录负责。我们已经纯化了MBF，结果表明它含有Swi6和一个110-120 kDa的蛋白，与Swi4(P120)不同，它与DNA接触。因此，我们认为SBF和MBF共享一个共同的调节亚基(Swi6)，但通过不同的DNA结合亚基识别它们的启动子元件。
Unlike early embryonic cleavage divisions in certain animals, cell-cycle progression in yeast and probably also in all metazoan somatic cells requires the periodic transcriptional activation of certain key genes. Thus far, the only clear examples are genes that encode a class of unstable 'cyclin' proteins, which bind and activate the cdc2/Cdc28 protein kinase: the G1-specific cyclins encoded by CLN1 and CLN2, a B-type cyclin implicated in DNA replication encoded by CLB5; and four B-type cyclins involved in mitosis encoded by CLB1, 2, 3, 4. CLN1, CLN2, and CLB5 are transcribed in late G1, as cells undergo Start. A transcription factor composed of Swi4 and Swi6 proteins (called SBF) activates CLN1 and CLN2 transcription via a positive feedback loop in which Cln proteins activate their own transcription. A different but related transcription factor called MBF seems responsible for the late G1-specific transcription of most DNA replication genes including CLB5. We have purified MBF and shown that it contains Swi6 and a 110-120 kDa protein distinct from Swi4 (p120) that contacts DNA. Thus, we propose that SBF and MBF share a common regulatory subunit (Swi6) but recognize their promoter elements via distinct DNA binding subunits.