SMAP2, a novel ARF GTPase-activating protein, interacts with clathrin and clathrin assembly protein and functions on the AP-1-positive early endosome/trans-Golgi network
SMAP2, a novel ARF GTPase-activating protein, interacts with clathrin and clathrin assembly protein and functions on the AP-1-positive early endosome/trans-Golgi network
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DOI：
10.1091/mbc.e05-10-0909
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发表时间：
2006-06-01
影响因子：
3.3
通讯作者：
Satake, Masanobu
中科院分区：
文献类型：
--
作者：
Natsume, Waka;Tanabe, Kenji;Satake, Masanobu
我们最近报道，SMAP 1，GTP酶激活蛋白（GAP）的Arf 6，直接与网格蛋白相互作用，并调节网格蛋白依赖的内吞转铁蛋白受体从质膜。在这里，我们发现了一个SMAP 1同源物，我们命名为SMAP 2。与SMAP 1一样，SMAP 2表现出GAP活性并与网格蛋白重链（CHC）相互作用。此外，我们发现SMAP 2与网格蛋白组装蛋白CALM相互作用。然而，与SMAP 1不同，SMAP 2似乎是体内Arf 1的调节因子，因为用GAP阴性SMAP 2突变体转染的细胞对布雷菲德菌素A具有抗性。SMAP 2与网格蛋白AP-1和EpsinR的衔接蛋白共定位在早期内体/trans-Golgi-network（TGN）上。此外，SMAP 2的过表达延迟了TGN 38/46分子在TGN上的积累。这表明SMAP 2以网格蛋白和AP-1依赖性方式在逆行的早期内体至TGN通路中起作用。因此，SMAP基因家族构成了一个重要的Arf GAP亚家族，每个SMAP成员在囊泡运输中发挥共同和不同的功能。
We recently reported that SMAP1, a GTPase-activating protein (GAP) for Arf6, directly interacts with clathrin and regulates the clathrin-dependent endocytosis of transferrin receptors from the plasma membrane. Here, we identified a SMAP1 homologue that we named SMAP2. Like SMAP1, SMAP2 exhibits GAP activity and interacts with clathrin heavy chain (CHC). Furthermore, we show that SMAP2 interacts with the clathrin assembly protein CALM. Unlike SMAP1, however, SMAP2 appears to be a regulator of Arf1 in vivo, because cells transfected with a GAP-negative SMAP2 mutant were resistant to brefeldin A. SMAP2 colocalized with the adaptor proteins for clathrin AP-1 and EpsinR on the early endosomes/trans-Golgi-network (TGN). Moreover, overexpression of SMAP2 delayed the accumulation of TGN38/46 molecule on the TGN. This suggests that SMAP2 functions in the retrograde, early endosome-to-TGN pathway in a clathrin- and AP-1-dependent manner. Thus, the SMAP gene family constitutes an important Arf GAP subfamily, with each SMAP member exerting both common and distinct functions in vesicle trafficking.