SUBUNITS SHARED BY EUKARYOTIC NUCLEAR-RNA POLYMERASES
SUBUNITS SHARED BY EUKARYOTIC NUCLEAR-RNA POLYMERASES
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DOI：
10.1101/gad.4.3.313
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发表时间：
1990-03-01
影响因子：
10.5
通讯作者：
YOUNG, RA
中科院分区：
文献类型：
--
作者：
WOYCHIK, NA;LIAO, SM;YOUNG, RA
RNA 聚合酶 I、II 和 III 共有三个亚基，这三个亚基在免疫学和生化上无法区分。对编码这些亚基（RPB5、RPB6 和 RPB8）的酿酒酵母基因进行了分离和测序，并推导了它们的转录起始位点。 RPB5 编码 25 kD 蛋白质，RPB6 和 18 kD 蛋白质，RPB8 编码 16 kD 蛋白质。这些基因是单拷贝，位于不同的染色体上，对于生存至关重要。这些基因是单拷贝的事实证实了先前的证据，表明 RNA 聚合酶 I、II 和 III 中的每个常见亚基都是相同的。此外，RPB6 的免疫沉淀共沉淀蛋白质，其大小与 RNA 聚合酶 I、II 和 III 亚基一致。酵母 RPB5 蛋白和先前表征的人 RNA 聚合酶亚基之间的序列相似性表明，核 RNA 聚合酶的共同亚基在真核生物中是高度保守的。所有三种核 RNA 聚合酶中都存在这些保守且必需的亚基，并且缺乏可识别的 DNA 和三磷酸核苷结合序列基序，表明这些常见亚基不具有催化作用，但对于 RNA 聚合酶共享的功能（如转录效率、核定位、酶稳定性或 rRNA、mRNA 和 tRNA 合成的协调调节）很重要。
RNA polymerases, I, II, and III share three subunits that are immunologically and biochemically indistinguishable. The Saccharomyces cerevisiae genes that encode these subunits (RPB5, RPB6, and RPB8) were isolated and sequenced, and their transcriptional start sites were deduced. RPB5 encodes a 25-kD protein, RPB6, and 18-kD protein, and RPB8, a 16-kD protein. These genes are single copy, reside on different chromosomes, and are essential for viability. The fact that the genes are single copy, corroborates previous evidence suggesting that each of the common subunits is identical in RNA polymerases I, II, and III. Furthermore, immunoprecipitation of RPB6 coprecipitates proteins whose sizes are consistent with RNA polymerase I, II, and III subunits. Sequence similarity between the yeast RPB5 protein and a previously characterized human RNA polymerase subunit demonstrates that the common subunits of the nuclear RNA polymerases are well conserved among eukaryotes. The presence of these conserved and essential subunits in all three nuclear RNA polymerases and the absence of recognizable sequence motifs for DNA and nucleoside triphosphate-binding indicate that the common subunits do not have a catalytic role but are important for a function shared by the RNA polymerases such as transcriptional efficiency, nuclear localization, enzyme stability, or coordinate regulation of rRNA, mRNA, and tRNA synthesis.