MULTIPLE UBIQUITIN-CONJUGATING ENZYMES PARTICIPATE IN THE IN-VIVO DEGRADATION OF THE YEAST MAT-ALPHA-2 REPRESSOR
MULTIPLE UBIQUITIN-CONJUGATING ENZYMES PARTICIPATE IN THE IN-VIVO DEGRADATION OF THE YEAST MAT-ALPHA-2 REPRESSOR
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DOI：
10.1016/0092-8674(93)90426-q
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发表时间：
1993-07-30
期刊：
影响因子：
64.5
通讯作者：
HOCHSTRASSER, M
中科院分区：
文献类型：
--
作者：
CHEN, P;JOHNSON, P;HOCHSTRASSER, M
泛素与蛋白质的结合是由一系列泛素结合酶(UBC)催化的。虽然这些酶在许多细胞过程中是必不可少的，但它们的分子功能仍然不清楚，因为还没有确定它们的生理靶点。在这里，我们证明了四种UBC蛋白(UBC4，UBC5，UBC6和UBC7)通过两条不同的泛素化途径靶向酵母MATalpha2转录调节因子进行细胞内降解。UBC6和UBC7定义了其中一条路径，并且可以物理关联。含有UBC6/Ubc7的复合体针对α2的Deg1降解信号，这一结论强调了UBC6由DOA2编码的结论，DOA2是一个先前与Deg1介导的降解有关的基因。这些数据揭示了不同的UBC酶在底物特异性上意外的重叠，并表明了一种底物选择的组合机制，其中UBC酶分配到多个泛素化复合体中。
Attachment of ubiquitin to proteins is catalyzed by a family of ubiquitin-conjugating (UBC) enzymes. Although these enzymes are essential for many cellular processes, their molecular functions remain unclear because no physiological target has been identified for any of them. Here we show that four UBC proteins (UBC4, UBC5, UBC6, and UBC7) target the yeast MATalpha2 transcriptional regulator for intracellular degradation by two distinct ubiquitination pathways. UBC6 and UBC7 define one of the pathways and can physically associate. The UBC6/UBC7-containing complex targets the Deg1 degradation signal of alpha2, a conclusion underscored by the finding that UBC6 is encoded by DOA2, a gene previously implicated in Deg1-mediated degradation. These data reveal an unexpected overlap in substrate specificity among diverse UBC enzymes and suggest a combinatorial mechanism of substrate selection in which UBC enzymes partition into multiple ubiquitination complexes.