Identification of a non-canonical tyrosine-based endocytic motif in an ionotropic receptor
Identification of a non-canonical tyrosine-based endocytic motif in an ionotropic receptor
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DOI：
10.1074/jbc.m204844200
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发表时间：
2002-09-20
影响因子：
4.8
通讯作者：
Murrell-Lagnado, RD
中科院分区：
文献类型：
--
作者：
Royle, SJ;Bobanovic, LK;Murrell-Lagnado, RD
通过改变插入和内化的相对速率，可以实现对某些嗜离子受体表面数量的快速调节。这些受体通过网格蛋白介导的途径内化；然而，对嗜离子受体内吞作用所必需的基序尚未被确定。在这里，我们确定了一个基序，它是组成性和激动剂调节的内化电离性P2X(4)受体所必需的。P2X(4) C端的三个氨基酸（Tyr（378）、Gly（381）和Leu(382)）组成了一个形式为YXXGL的基于酪氨酸的非规范排序信号。我们发现P2X(4)蛋白存在于从大鼠脑分离的网格蛋白包被的囊泡中，并且P2X(4) C末端的谷胱甘肽s转移酶融合降低了脑提取物中的衔接蛋白-2复合物。适配器蛋白2的mu2亚基的酪氨酸结合袋或受体C端YXXGL基序的突变导致受体内化减少和P2X受体表面表达的急剧增加(4)。YXXGL基序代表了一个非典型的基于酪氨酸的分类信号，这对于P2X(4)受体的有效内吞是必要的。类似的基序存在于其他受体中，可能对其功能表达的控制很重要。
Rapid modulation of the surface number of certain ionotropic receptors is achieved by altering the relative rates of insertion and internalization. These receptors are internalized by a clathrin-mediated pathway; however, a motif that is necessary for endocytosis of ionotropic receptors has not yet been identified. Here, we identified a motif that is required for constitutive and agonist-regulated internalization of the ionotropic P2X(4) receptor. Three amino acids in the C terminus of P2X(4) (Tyr(378), Gly(381), and Leu(382)) compose a non-canonical tyrosine-based sorting signal of the form YXXGL. We found that P2X(4) protein was present in clathrin-coated vesicles isolated from rat brain and that a glutathione S-transferase fusion of the P2X(4) C terminus pulled down the adaptor protein-2 complex from brain extract. Mutation of either the tyrosine-binding pocket of the mu2 subunit of adaptor protein-2 or the YXXGL motif in the receptor C terminus caused a decrease in receptor internalization and a dramatic increase in the surface expression of P2X(4) receptors. The YXXGL motif represents a non-canonical tyrosine-based sorting signal that is necessary for efficient endocytosis of the P2X(4) receptor. Similar motifs are present in other receptors and may be important for the control of their functional expression.