Tollip and Tom1 form a complex and recruit ubiquitin-conjugated proteins onto early endosomes
Tollip and Tom1 form a complex and recruit ubiquitin-conjugated proteins onto early endosomes
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DOI：
10.1074/jbc.m400059200
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发表时间：
2004-06-04
影响因子：
4.8
通讯作者：
Nakayama, K
中科院分区：
文献类型：
--
作者：
Katoh, Y;Shiba, Y;Nakayama, K
Tom1（Myb1 的靶标）是一种功能未知的蛋白质。 Tom1 及其相关 Tom1L1 具有 N 端 VHS (Vps27p/Hrs/Stam) 结构域，后跟 GAT（GGA 和 Tom1）结构域，这两个结构域也存在于 GGA（高尔基体定位、γ-适应素耳结构域同源性、ADP-核糖基化因子结合蛋白）蛋白家族中。尽管 GGA 蛋白的 VHS 和 GAT 结构域分别与跨膜货物蛋白和小 GTPase ADP 核糖基化因子结合，但 Tom1 的 VHS 和 GAT 结构域无法与这些蛋白相互作用。在本研究中，我们证明 Tom1 和 Tom1L1 的 GAT 结构域与泛素和 Tollip（Toll 相互作用蛋白）相互作用。泛素结合 Tom1、Tom1L1 和 GGA 蛋白的 GAT 结构域，而 Tollip 与 Tom1 和 Tom1L1 特异性相互作用。泛素和 Tollip 以互斥的方式结合到 Tom1-GAT 结构域的重叠区域。 Tom1 在细胞中表达时主要在细胞质中表达。另一方面，Tollip 定位于早期内体并招募 Tom1 和泛素化蛋白。这些观察结果表明 Tollip 和 Tom1 形成复合物并调节泛素化蛋白的内体运输。
Tom1 (target of Myb1) is a protein of unknown function. Tom1 and its relative Tom1L1 have an N-terminal VHS (Vps27p/Hrs/Stam) domain followed by a GAT (GGA and Tom1) domain, both of which are also found in the GGA (Golgi-localizing, gamma-adaptin ear domain homology, ADP-ribosylation factor-binding protein) family of proteins. Although the VHS and GAT domains of GGA proteins bind to transmembrane cargo proteins and the small GTPase ADP-ribosylation factor, respectively, the VHS and GAT domains of Tom1 are unable to interact with these proteins. In this study, we show that the GAT domains of Tom1 and Tom1L1 interact with ubiquitin and Tollip (Toll-interacting protein). Ubiquitin bound the GAT domains of Tom1, Tom1L1, and GGA proteins, whereas Tollip interacted specifically with Tom1 and Tom1L1. Ubiquitin and Tollip bound to an overlapping region of the Tom1-GAT domain in a mutually exclusive manner. Tom1 was predominantly cytosolic when expressed in cells. On the other hand, Tollip was localized on early endosomes and recruited Tom1 and ubiquitinated proteins. These observations suggest that Tollip and Tom1 form a complex and regulate endosomal trafficking of ubiquitinated proteins.