The synaptojanin-like protein Inp53/Sj13 functions with clathrin in a yeast TGN-to-endosome pathway distinct from the GGA protein-dependent pathway
The synaptojanin-like protein Inp53/Sj13 functions with clathrin in a yeast TGN-to-endosome pathway distinct from the GGA protein-dependent pathway
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DOI：
10.1091/mbc.e02-10-0686
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发表时间：
2003-04-01
影响因子：
3.3
通讯作者：
Nothwehr, SF
中科院分区：
文献类型：
--
作者：
Ha, SA;Torabinejad, J;Nothwehr, SF
经常在TGN和内体之间循环的酵母TGN驻留蛋白质比其他蛋白质更慢地运输到前液泡/晚期内体隔室（PVC）。然而，TGN蛋白运输到PVC的Inp 53 p缺乏功能的突变体加速。Inp 53 p含有SacI多磷酸肌醇磷酸酶结构域、5-磷酸酶结构域和富含脯氨酸的结构域。在这里，我们表明，所有三个域都需要介导的“缓慢交付”的TGN蛋白到PVC。虽然富含脯氨酸的结构域的删除并不影响一般的膜协会，它导致本地化变得不那么具体。富含脯氨酸的结构域被证明与两种蛋白质结合，包括网格蛋白重链Chc 1 p。与chc 1突变体不同，inp 53突变体不会将TGN蛋白错误定位于细胞表面，这与Chc 1 p和Inp 53 p作用于共同的囊泡运输步骤但Chc 1 p也用于其他步骤的想法一致。与AP-1接头复合物中的突变一样，INP 53中的突变在与GGA蛋白中的突变组合时表现出合成生长和转运缺陷。与其他最近的研究一起，我们的研究结果表明，Inp 53 p和AP-1/网格蛋白一起作用于TGN-早期内体途径，不同于GGA/网格蛋白介导的直接TGN-至-PVC途径。
Yeast TGN resident proteins that frequently cycle between the TGN and endosomes are much more slowly transported to the prevacuolar /late endosomal compartment (PVC) than other proteins. However, TGN protein transport to the PVC is accelerated in mutants lacking function of Inp53p. Inp53p contains a SacI polyphosphoinositide phosphatase domain, a 5-phosphatase domain, and a proline-rich domain. Here we show that all three domains are required to mediate "slow delivery" of TGN proteins into the PVC. Although deletion of the proline-rich domain did not affect general membrane association, it caused localization to become less specific. The proline-rich domain was shown to bind to two proteins, including clathrin heavy chain, Chc1p. Unlike chc1 mutants, inp53 mutants do not mislocalize TGN proteins to the cell surface, consistent with the idea that Chc1p and Inp53p act at a common vesicular trafficking step but that Chc1p is used at other steps also. Like mutations in the AP-1 adaptor complex, mutations in INP53 exhibit synthetic growth and transport defects when combined with mutations in the GGA proteins. Taken together with other recent studies, our results suggest that Inp53p and AP-1/clathrin act together in a TGN-to-early endosome pathway distinct from the direct TGN-to-PVC pathway mediated by GGA/clathrin.