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首页> 外文期刊>Molecular and Cellular Biology >Role of maturation-promoting factor (p34cdc2-cyclin B) in differential expression of the Xenopus oocyte and somatic-type 5S RNA genes.
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Role of maturation-promoting factor (p34cdc2-cyclin B) in differential expression of the Xenopus oocyte and somatic-type 5S RNA genes.

机译：成熟促进因子（p34cdc2-cyclin B）在非洲爪蟾卵母细胞和体细胞型5S RNA基因差异表达中的作用。

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Transcription of 5S rRNA and tRNA genes by RNA polymerase III (pol III) in cytosolic extracts of unfertilized Xenopus eggs and in a reconstituted system derived from Xenopus oocytes is repressed by the action of one or more mitotic protein kinases. Repression is due to the phosphorylation of a component of the pol III transcription apparatus. We find that the maturation/mitosis-promoting factor kinase (MPF, p34cdc2-cyclin B) can directly mediate this repression in vitro. Affinity-purified MPF and immune complexes formed with antibodies to the protein subunits of MPF (p34cdc2 and cyclin B) retain both histone H1 kinase activity and the capacity to repress transcription in the reconstituted transcription system. Transcription complexes of oocyte-type 5S RNA genes and tRNA genes are quantitatively more sensitive to MPF repression than the corresponding transcription complexes of the somatic-type 5S RNA gene. The differential transcription of oocyte- and somatic-type genes observed during early Xenopus embryogenesis has been reproduced with the reconstituted transcription system and affinity-purified MPF. This differential transcription may be due to the instability of transcription complexes on the oocyte-type genes and the heightened sensitivity of soluble transcription factors to inactivation by mitotic phosphorylation. Our results suggest that MPF may play a role in vivo in the establishment of the embryonic pattern of pol III gene expression.
机译：一种或多种有丝分裂蛋白激酶的作用抑制了未受精爪蟾卵细胞质提取物中和源自爪蟾卵母细胞的重组系统中RNA聚合酶III（pol III）对5S rRNA和tRNA基因的转录。抑制是由于pol III转录装置的一个组件的磷酸化。我们发现，成熟/促有丝分裂促进因子激酶（MPF，p34cdc2-cyclin B）可以直接介导这种抑制作用。亲和纯化的MPF和与MPF蛋白亚基（p34cdc2和cyclin B）抗体形成的免疫复合物既保留了组蛋白H1激酶活性，又保留了重组转录系统中抑制转录的能力。卵母细胞型5S RNA基因和tRNA基因的转录复合物比体细胞型5S RNA基因的相应转录复合物在数量上对MPF抑制更为敏感。在非洲爪蟾早期胚胎发生过程中观察到的卵母细胞和体细胞类型基因的差异转录已通过重组转录系统和亲和纯化的MPF进行了复制。这种差异转录可能是由于卵母细胞型基因上转录复合物的不稳定性以及可溶性转录因子对有丝分裂磷酸化引起的失活敏感性提高所致。我们的结果表明，MPF可能在体内建立pol III基因表达的胚胎模式中发挥作用。

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