酵母菌第一腺嘌呤核苷二磷酸核醣化因子相似蛋白與Ypt6p相關路徑之功能性探討

Abstract

ARLs家族蛋白已經被發現在囊泡運輸扮演著重要的腳色，在酵母菌中，Arl1p及下游的Imh1p被認為與Rab家族的Ypt6p是兩條冗餘路徑，許多ypt6Δ的表型都可被高表現量的Arl1p及Imh1p所抑制。在這篇研究中，我們發現Arl1p路徑與Ypt6p路徑藉由GARP complex連結，另外，Imh1p胺基端的結構似乎對與GARP complex的交互作用扮演著相當重要的角色，我們更進一步發現，在野生酵母菌中雖然一般條件下著樣子的交互作用非常微弱，但在內質網壓力下，這樣子的交互作用卻對GARP complex執行核內體到高基氏體的逆向運輸相當重要。我們也發現了一個目前未知功能的高基氏體蛋白：Sft2p同樣參與在Arl1p路徑之中，在研究的最後我們探索了GARP complex作為Arl1p的GEF的可能性。

ARF-like (ARLs) protein have already known to play a role in vesicle trafficking. In yeast, Arl1p and its effector Imh1p is thought to be a redundant pathway with Rab family protein Ypt6p. Various phenotypes in ypt6Δ could be suppress through overexpression of Arl1p and Imh1p. In this study, we find that Arl1p-Imh1p pathway cross talk with Ypt6 pathway through GARP complex. The N-terminal of Imh1 seems plays a important role to interact through GARP complex. Furthermore, we find that although in normal condition such cross talk is very miner, this cross talk through GARP complex is important to against endosome-to-Golgi transport defect under ER stress. We also identify Sft2p, a unknown function protein localize to TGN, also participate in Arl1p-Imh1p pathway. In the end we give a hint that GARP complex subiut Vps53p might be a GEF of Arl1p.