STAM and Hrs are subunits of a multivalent ubiquitin-binding complex on early endosomes
STAM and Hrs are subunits of a multivalent ubiquitin-binding complex on early endosomes
复制标题
DOI：
10.1074/jbc.m210843200
复制
发表时间：
2003-04-04
影响因子：
4.8
通讯作者：
Stenmark, H
中科院分区：
文献类型：
--
作者：
Bache, KG;Raiborg, C;Stenmark, H
STAM 1和STAM 2，已被确定为受体信号传导和运输的调节器，直接与Hrs相互作用，其介导泛素化膜蛋白的内吞分选。STAM蛋白与参与Hrs靶向内体的相同卷曲螺旋结构域相互作用。在这项工作中，我们表明，STAM 1和STAM 2，以及内吞调节蛋白，Eps 15，可以与Hrs从膜和胞质组分和重组Hrs，STAM 1/STAM 2，和Eps 15形成三元复合物共免疫沉淀。我们发现Hrs的过度表达导致STAM 2向核内体膜的强烈募集。此外，STAM 2，像Hrs和Eps 15，结合泛素，和Hrs，STAM 2，和Eps 15共定位与泛素化的蛋白质在网格蛋白含有内体微结构域。Hrs、STAM 2、Eps 15和网格蛋白在内体膜上的定位由AAA ATP酶mVps 4控制，其与多泡体形成有关。小干扰RNA对细胞Hrs的消耗导致STAM 2向核内体膜的募集大大减少，并且内吞的表皮生长因子受体的降解受损。我们建议，Hrs，Eps 15，和STAM蛋白功能的多价复合物，分类泛素化蛋白进入多泡体途径。
STAM1 and STAM2, which have been identified as regulators of receptor signaling and trafficking, interact directly with Hrs, which mediates the endocytic sorting of ubiquitinated membrane proteins. The STAM proteins interact with the same coiled-coil domain that is involved in the targeting of Hrs to endosomes. In this work, we show that STAM1 and STAM2, as well as an endocytic regulator protein, Eps15, can be co-immunoprecipitated with Hrs both from membrane and cytosolic fractions and that recombinant Hrs, STAM1/STAM2, and Eps15 form a ternary complex. We find that overexpression of Hrs causes a strong recruitment of STAM2 to endosome membranes. Moreover, STAM2, like Hrs and Eps15, binds ubiquitin, and Hrs, STAM2, and Eps15 colocalize with ubiquitinated proteins in clathrin-containing endosomal microdomains. The localization of Hrs, STAM2, Eps15, and clathrin to endosome membranes is controlled by the AAA ATPase mVps4, which has been implicated in multivesicular body formation. Depletion of cellular Hrs by small interfering RNA results in a strongly reduced recruitment of STAM2 to endosome membranes and an impaired degradation of endocytosed epidermal growth factor receptors. We propose that Hrs, Eps15, and STAM proteins function in a multivalent complex that sorts ubiquitinated proteins into the multivesicular body pathway.