Association of protein-tyrosine phosphatase MEG2 via its Sec14p homology domain with vesicle-trafficking proteins
Association of protein-tyrosine phosphatase MEG2 via its Sec14p homology domain with vesicle-trafficking proteins
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DOI：
10.1074/jbc.m608682200
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发表时间：
2007-05-18
影响因子：
4.8
通讯作者：
Mustelin, Tomas
中科院分区：
文献类型：
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作者：
Saito, Kan;Williams, Scott;Mustelin, Tomas
蛋白酪氨酸磷酸酶PTPMEG 2位于分泌囊泡的封闭膜的细胞质面上，在那里它通过使N-乙基马来酰亚胺敏感因子（囊泡融合的关键调节因子）去磷酸化来促进同型囊泡融合，从而调节囊泡大小。在这里，我们解决的问题PTPMEG 2是如何针对这个亚细胞位置。使用一系列的缺失突变体，我们精确定位的N-末端SEC 14 p同源（SEC 14）结构域的PTPMEG 2，残基1 - 261，作为区域含有分泌囊泡靶向信号。该结构域，单独或附加到异源蛋白，定位于细胞内囊泡膜。酵母双杂交筛选鉴定了许多分泌囊泡蛋白，其直接与PTPMEG 2的SEC 14结构域相互作用，提供了PTPMEG 2靶向分泌囊泡的机制。发现两种这样的蛋白质，甘露糖6-磷酸受体相互作用蛋白TIP 47和Arfaptin 2，在过表达时改变PTPMEG 2定位，并且TIP 47的消除导致PTPMEG 2功能的丧失。我们认为PTPMEG 2的N端是通过与其他参与细胞内转运的蛋白质结合而将磷酸酶靶向分泌囊泡区所必需的。
The protein-tyrosine phosphatase PTPMEG2 is located on the cytoplasmic face of the enclosing membrane of secretory vesicles, where it regulates vesicle size by promoting homotypic vesicle fusion by dephosphorylating N-ethylmaleimide-sensitive factor, a key regulator of vesicle fusion. Here we address the question of how PTPMEG2 is targeted to this subcellular location. Using a series of deletion mutants, we pinpointed the N-terminal Sec14p homology ( SEC14) domain of PTPMEG2, residues 1 - 261, as the region containing the secretory vesicle targeting signal. This domain, alone or appended to a heterologous protein, was localized to intracellular vesicle membranes. Yeast two-hybrid screening identified a number of secretory vesicle proteins that interacted directly with the SEC14 domain of PTPMEG2, providing a mechanism for PTPMEG2 targeting to secretory vesicles. Two such proteins, mannose 6-phosphate receptor-interacting protein TIP47 and Arfaptin2, were found to alter PTPMEG2 localization when overexpressed, and elimination of TIP47 resulted in loss of PTPMEG2 function. Weconclude that the N terminus of PTPMEG2 is necessary for the targeting of this phosphatase to the secretory vesicle compartment by association with other proteins involved in intracellular transport.