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首页> 外文期刊>Molecular and Cellular Biology >Inactivation of the protein phosphatase 2A regulatory subunit A results in morphological and transcriptional defects in Saccharomyces cerevisiae.
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Inactivation of the protein phosphatase 2A regulatory subunit A results in morphological and transcriptional defects in Saccharomyces cerevisiae.

机译：蛋白磷酸酶2A调节亚基A的失活导致啤酒酵母中的形态和转录缺陷。

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We have determined that TPD3, a gene previously identified in a screen for mutants defective in tRNA biosynthesis, most likely encodes the A regulatory subunit of the major protein phosphatase 2A species in the yeast Saccharomyces cerevisiae. The predicted amino acid sequence of the product of TPD3 is highly homologous to the sequence of the mammalian A subunit of protein phosphatase 2A. In addition, antibodies raised against Tpd3p specifically precipitate a significant fraction of the protein phosphatase 2A activity in the cell, and extracts of tpd3 strains yield a different chromatographic profile of protein phosphatase 2A than do extracts of isogenic TPD3 strains. tpd3 deletion strains generally grow poorly and have at least two distinct phenotypes. At reduced temperatures, tpd3 strains appear to be defective in cytokinesis, since most cells become multibudded and multinucleate following a shift to 13 degrees C. This is similar to the phenotype obtained by overexpression of the protein phosphatase 2A catalytic subunit or by loss of CDC55, a gene that encodes a protein with homology to a second regulatory subunit of protein phosphatase 2A. At elevated temperatures, tpd3 strains are defective in transcription by RNA polymerase III. Consistent with this in vivo phenotype, extracts of tpd3 strains fail to support in vitro transcription of tRNA genes, a defect that can be reversed by addition of either purified RNA polymerase III or TFIIIB. These results reinforce the notion that protein phosphatase 2A affects a variety of biological processes in the cell and provide an initial identification of critical substrates for this phosphatase.
机译：我们已经确定，TPD3是一种先前在tRNA生物合成中缺陷突变体的筛选中鉴定的基因，最有可能编码啤酒酵母中主要蛋白磷酸酶2A的A调节亚基。 TPD3产物的预测氨基酸序列与蛋白磷酸酶2A的哺乳动物A亚基的序列高度同源。此外，针对Tpd3p的抗体特异性地在细胞中沉淀了大部分蛋白质磷酸酶2A活性，并且tpd3菌株的提取物与同基因TPD3菌株的提取物产生了不同的蛋白质磷酸酶2A色谱特征。 tpd3缺失菌株通常生长不良，并具有至少两个不同的表型。在降低的温度下，tpd3菌株似乎在胞质分裂方面存在缺陷，因为大多数细胞转变为13摄氏度后会变成多预算和多核的。这类似于通过过度表达蛋白磷酸酶2A催化亚基或通过CDC55缺失获得的表型，编码与蛋白质磷酸酶2A的第二个调节亚基同源的蛋白质的基因。在升高的温度下，tpd3菌株在RNA聚合酶III的转录中存在缺陷。与这种体内表型一致，tpd3菌株的提取物不能支持tRNA基因的体外转录，这种缺陷可以通过添加纯化的RNA聚合酶III或TFIIIB来逆转。这些结果强化了蛋白质磷酸酶2A影响细胞中各种生物学过程的观念，并为该磷酸酶的关键底物提供了初步的鉴定。

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