Identification of a putative effector protein for rab11 that participates in transferrin recycling.
Identification of a putative effector protein for rab11 that participates in transferrin recycling.
复制标题
鉴定参与转铁蛋白回收的假定 rab11 效应蛋白。
DOI：
10.1073/pnas.96.6.2840
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发表时间：
1999
影响因子：
11.1
通讯作者：
Sabatini,DD
中科院分区：
文献类型：
--
作者：
Zeng,J;Ren,M;Gravotta,D;DeLemos-Chiarandini,C;Lui,M;Erdjument-Bromage,H;Tempst,P;Xu,G;Shen,TH;Morimoto,T;Adesnik,M;Sabatini,DD
我们已经鉴定并克隆了912-AA蛋白Rab11BP的cDNA，该蛋白与含有GTP的活性形式的Rab11相互作用，Rab11是一种在受体循环中发挥关键作用的GTP结合蛋白。虽然Rab11BP主要是胞液的，但有相当一部分与Rab11共存于分类和回收亚室的内体膜上。在Rab11与天然Rab11BP的体外结合中，后者需要部分变性，以暴露位于残基334和504之间的内部结合部位，该结合部位显然被蛋白质的C-末端部分所掩盖，该部分包括六个被称为WD40结构域的重复序列。在细胞内，Rab11BP必须经历一个构象变化，其中Rab11结合位点暴露，因为当在转基因细胞中与Rab11共表达时，两种蛋白形成了丰富的与膜相关的复合体。此外，尽管过表达Rab11BP并不影响转铁蛋白循环，但过表达包括Rab11结合位点但缺乏WD40结构域的截短形式的Rab11BP(1-504)对循环的抑制作用与不与GTP结合的显性负Rab11突变蛋白一样强烈。值得注意的是，当细胞还表达一种C末端缺失的、不可戊烯基化的Rab11形式时，截短的Rab11BP引起的抑制完全被阻止，这种形式本身对循环没有影响。我们认为Rab11BP是Rab11的效应物，其与该GTP结合蛋白的结合依赖于另一个促进Rab11BP中Rab11结合位点的揭开的膜相关因子的作用。
We have identified and cloned the cDNA for a 912-aa protein, rab11BP, that interacts with the GTP-containing active form of rab11, a GTP-binding protein that plays a critical role in receptor recycling. Although rab11BP is primarily cytosolic, a significant fraction colocalizes with rab11 in endosomal membranes of both the sorting and recycling subcompartments.In vitrobinding of rab11 to native rab11BP requires partial denaturation of the latter to expose an internal binding site located between residues 334 and 504 that is apparently masked by the C-terminal portion of the protein, which includes six repeats known as WD40 domains. Within the cell, rab11BP must undergo a conformational change in which the rab11-binding site becomes exposed, because when coexpressed with rab11 in transfected cells the two proteins formed abundant complexes in association with membranes. Furthermore, although overexpression of rab11BP did not affect transferrin recycling, overexpression of a truncated form of the protein, rab11BP(1–504), that includes the rab11-binding site but lacks the WD40 domains inhibited recycling as strongly as does a dominant negative rab11 mutant protein that does not bind GTP. Strikingly, the inhibition caused by the truncated rab11BP was prevented completely when the cells also expressed a C-terminally deleted, nonprenylatable form of rab11 that, by itself, has no effect on recycling. We propose that rab11BP is an effector for rab11, whose association with this GTP-binding protein is dependent on the action of another membrane-associated factor that promotes the unmasking of the rab11-binding site in rab11BP.