Hrs sorts ubiquitinated proteins into clathrin-coated microdomains of early endosomes
Hrs sorts ubiquitinated proteins into clathrin-coated microdomains of early endosomes
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DOI：
10.1038/ncb791
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发表时间：
2002-05-01
影响因子：
21.3
通讯作者：
Stenmark, H
中科院分区：
文献类型：
--
作者：
Raiborg, C;Bache, KG;Stenmark, H
内吞作用后，一些膜蛋白从早期内体再循环至质膜，而另一些则转运至晚期内体和溶酶体进行降解（1）。与小多肽泛素的缀合是溶酶体分选的信号（2，3）。我们发现肝细胞生长因子调节的酪氨酸激酶底物Hrs（4）参与了泛素化膜蛋白的内体分选。Hrs包含网格蛋白结合结构域（5），通过电子显微镜，我们发现Hrs定位于早期内体上的平坦网格蛋白晶格。我们证明，Hrs直接结合到泛素的方式的泛素相互作用基序（UIM），和泛素化的蛋白质本地化的Hrs和网格蛋白含有微结构域。而内吞转铁蛋白受体不能与Hrs共定位并迅速再循环到细胞表面，融合到泛素的转铁蛋白受体与Hrs相互作用，定位到含Hrs和网格蛋白的微结构域，并被分选到降解途径。Hrs的过表达强烈地且特异性地通过需要功能性UIM的机制抑制泛素化转铁蛋白受体的再循环。我们的结论是，Hrs将泛素化的膜蛋白分类到早期内体的网格蛋白包被的微区中，从而阻止它们再循环到细胞表面。
After endocytosis, some membrane proteins recycle from early endosomes to the plasma membrane whereas others are transported to late endosomes and lysosomes for degradation(1). Conjugation with the small polypeptide ubiquitin is a signal for lysosomal sorting(2,3). Here we show that the hepatocyte growth factor-regulated tyrosine kinase substrate, Hrs(4), is involved in the endosomal sorting of ubiquitinated membrane proteins. Hrs contains a clathrin-binding domain(5), and by electron microscopy we show that Hrs localizes to flat clathrin lattices on early endosomes. We demonstrate that Hrs binds directly to ubiquitin by way of a ubiquitin-interacting motif (UIM), and that ubiquitinated proteins localize specifically to Hrs- and clathrin-containing microdomains. Whereas endocytosed transferrin receptors fail to colocalize with Hrs and rapidly recycle to the cell surface, transferrin receptors that are fused to ubiquitin interact with Hrs, localize to Hrs- and clathrin-containing microdomains and are sorted to the degradative pathway. Overexpression of Hrs strongly and specifically inhibits recycling of ubiquitinated transferrin receptors by a mechanism that requires a functional UIM. We conclude that Hrs sorts ubiquitinated membrane proteins into clathrin-coated microdomains of early endosomes, thereby preventing their recycling to the cell surface.