Subcellular localization, stoichiometry, and protein levels of 26 S proteasome subunits in yeast
Subcellular localization, stoichiometry, and protein levels of 26 S proteasome subunits in yeast
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DOI：
10.1074/jbc.274.31.21943
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发表时间：
1999-07-30
影响因子：
4.8
通讯作者：
Johnston, SA
中科院分区：
文献类型：
--
作者：
Russell, SJ;Steger, KA;Johnston, SA
真核生物的26 S蛋白酶体负责通过泛素系统降解蛋白质。酵母是了解真核生物蛋白酶体结构和功能的重要模式生物，为了定量表征蛋白酶体，我们确定了蛋白酶体亚基的定位、细胞水平和化学计量，蛋白酶体调节复合物的两个ATP酶组分Suga/Rpt 4和Sug 1/Rpt 6以及20 S蛋白酶体的一个亚基Pre 1的亚细胞定位，通过免疫荧光法测定。与多细胞生物中的发现相反，这些蛋白质在整个细胞周期中几乎专门定位于细胞核。我们还确定了这些蛋白酶体亚基的细胞丰度和化学计量。Sug 1/Rpt 6、Sug 2/Rpt 4和Pre 1以大致相等的化学计量存在，丰度为15，000 - 30，000分子/细胞，对应于细胞核中13-26 μ M的浓度。此外，与哺乳动物细胞相比，我们没有发现酵母中蛋白酶体含有p27的“调节剂”的证据。这些信息将有助于比较和对比酵母和哺乳动物的蛋白酶体，并应有助于了解这种复杂的功能机制。
The 26 S proteasome of eukaryotes is responsible for the degradation of proteins targeted for proteolysis by the ubiquitin system. Yeast has been an important model organism for understanding eukaryotic proteasome structure and function, Toward a quantitative characterization of the proteasome, we have determined the localization, cellular levels, and stoichiometry of proteasome subunits, The subcellular localization of two ATPase components of the regulatory complex of the proteasome, Suga/Rpt4 and Sug1/Rpt6, and a subunit of the 20 S proteasome, Pre1, were determined by immunofluorescence, In contrast to findings in multicellular organisms, these proteins are localized almost exclusively to the nucleus throughout the cell cycle. We have also determined the cellular abundance and stoichiometry of these proteasome subunits. Sug1/Rpt6, Sug2/Rpt4, and Pre1 are present in roughly equal stoichiometry with an abundance of 15,000-30,000 molecules/cell, corresponding to a concentration of 13-26 mu M in the nucleus. Also, in contrast to mammalian cells, we find no evidence of a p27-containing "modulator" of the proteasome in yeast. This information will be useful in comparing and contrasting the yeast and mammalian proteasomes and should contribute to a mechanistic understanding of how this complex functions.