Clathrin anchors deubiquitinating enzymes, AMSH and AMSH-like protein, on early endosomes
Clathrin anchors deubiquitinating enzymes, AMSH and AMSH-like protein, on early endosomes
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DOI：
10.1111/j.1365-2443.2006.00963.x
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发表时间：
2006-06-01
期刊：
影响因子：
2.1
通讯作者：
Komada, Masayuki
中科院分区：
文献类型：
--
作者：
Nakamura, Michihiko;Tanaka, Nobuyuki;Komada, Masayuki
泛素化膜蛋白的内体分选用于运输到溶酶体由两种泛素结合蛋白Hrs和STAM的复合物执行，其定位于具有平坦网格蛋白外壳的早期内体的微结构域上。AMSH是一种去泛素化酶，与STAM相互作用，并参与表皮生长因子受体的下调。AMSH有一个类似物AMSH样蛋白（AMSH-LP）。在这里，我们表明，AMSH-LP也是一种去泛素化酶，作用于早期内体。我们进一步表明，AMSH和AMSH-LP结合网格蛋白重链的末端结构域通过一个新的网格蛋白结合位点之间保守的这些蛋白质。外源表达的AMSH和AMSH-LP与网格蛋白共定位于早期内体上。然而，从蛋白质中删除网格蛋白结合位点，以及RNA干扰介导的网格蛋白重链耗竭，导致AMSH和AMSH-LP无法定位在内体上。相反，缺乏结合STAM能力的AMSH突变体通常位于内体上。我们认为AMSH和AMSH-LP通过与网格蛋白外壳的相互作用锚定在早期内体膜上。
Endosomal sorting of ubiquitinated membrane proteins for trafficking to lysosomes is executed by a complex of two ubiquitin-binding proteins, Hrs and STAM, that localizes on a microdomain of early endosomes with a flat clathrin coat. AMSH is a deubiquitinating enzyme that interacts with STAM and is implicated in the down-regulation of epidermal growth factor receptor. AMSH has a close homolog, AMSH-like protein (AMSH-LP). Here we show that AMSH-LP is also a deubiquitinating enzyme that acts on early endosomes. We further show that AMSH and AMSH-LP bind to the terminal domain of clathrin heavy chain via a novel clathrin-binding site conserved between these proteins. Exogenously expressed AMSH and AMSH-LP co-localized with clathrin on early endosomes. However, deletion of the clathrin-binding site from the proteins, as well as RNA interference-mediated depletion of clathrin heavy chain, resulted in a failure of AMSH and AMSH-LP to localize on endosomes. In contrast, a mutant of AMSH that lacks the ability to bind STAM localized normally on endosomes. We suggest that AMSH and AMSH-LP are anchored on the early endosomal membrane via interaction with the clathrin coat.