Ess1 is a prolyl isomerase that regulates the structure and function of eukaryotic RNA polymerase II. Ess1 works by catalyzing the cis/trans conversion of pSer5–Pro6 bonds, and to a lesser extent pSer2–Pro3 bonds, within the carboxy-terminal domain (CTD) of Rpb1, the largest subunit of RNA pol II. Ess1 is conserved in organisms ranging from yeast to humans. In budding yeast, Ess1 is essential for growth and is required for efficient transcription initiation and termination, RNA processing, and suppression of cryptic transcription. In mammals, Ess1 (called Pin1) functions in a variety of pathways, including transcription, but it is not essential. Recent work has shown that Ess1 coordinates the binding and release of CTD-binding proteins that function as co-factors in the RNA pol II complex. In this way, Ess1 plays an integral role in writing (and reading) the so-called CTD code to promote production of mature RNA pol II transcripts including non-coding RNAs and mRNAs.
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机译：Ess1是脯氨酰异构酶，可调节真核RNA聚合酶II的结构和功能。 Ess1通过在RNA pol II的最大亚基Rpb1的羧基末端结构域（CTD）内催化pSer5-Pro6键的顺式/反式转化，并在较小程度上催化pSer2-Pro3键。 Ess1在从酵母到人类的各种生物中都是保守的。在发芽酵母中，Ess1对于生长至关重要，并且对于有效的转录起始和终止，RNA处理以及隐性转录的抑制也是必需的。在哺乳动物中，Ess1（称为Pin1）在多种途径中起作用，包括转录，但这不是必需的。最近的工作表明，Ess1协调了CTD结合蛋白的结合和释放，这些蛋白在RNA pol II复合物中起辅助因子的作用。通过这种方式，Ess1在编写（和读取）所谓的CTD代码中起着不可或缺的作用，以促进产生成熟的RNA pol II转录本，包括非编码RNA和mRNA。
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