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標題: | 酵母菌第一腺嘌呤核苷二磷酸核醣化因子相似蛋白與其結合蛋白的功能性探討 Functional Characterization of ADP-Ribosylation Factor-Like Protein 1 and its Interacting Proteins in Saccharomyces cerevisiae |
作者: | Kuan-Yu Chen 陳冠毓 |
指導教授: | 李芳仁(FANG-JEN, LEE) |
關鍵字: | 第一腺嘌呤核苷,二磷酸核醣化因子相似蛋白,腺嘌呤核苷,二磷酸核醣化因子,高基氏體蛋白, ARL1,ARF,golgin,Imh1, |
出版年 : | 2011 |
學位: | 博士 |
摘要: | 第一腺嘌呤核苷二磷酸核醣化因子相似蛋白(ARL1)是腺嘌呤核苷二磷酸核醣化因子(ADP-ribosylation factor, ARF)家族的一員。它們皆為小型鳥糞嘌呤核苷結合蛋白。ARF家族成員負責著細胞內的囊泡運輸、磷脂酶的活化、參與磷脂三激酶的訊息調控等等的功能。目前雖然已知有許多ARL的存在但對其功能卻仍幾乎是一無所知。近來,我們實驗室已經發現了Syt1p是Arl1p蛋白的鳥糞嘌呤核苷三磷酸(GTP)交換蛋白(GEF)。他會促使Arl1p與鳥糞嘌呤核苷三磷酸結合,並吸引其下游作用蛋白 Imh1p至高基氏體上,最後經由其活化蛋白(GAP)Gcs1p水解鳥糞嘌呤核苷三磷酸。Imh1p是高基氏體蛋白(golgin)的一種。而雖然在動物細胞中,高基氏體蛋白已被報導與調控、維持高基氏體的功能有關,但在酵母菌中,Imh1p的功能仍然不清楚。在本篇論文裡,我發現Imh1p在調控Arl1p的去活化中扮演一定的腳色。在酵母菌中去除IMH1基因會造成Arl1p失去與鳥糞嘌呤核苷三磷酸的結合,而造成Arl1p失去其正常應位於高基氏體的位置。在生體外,Imh1p與Gcs1p會互相競爭與Arl1p結合,Arl1p與Imh1p的結合會減少Gcs1p去活化Arl1p-GTP的能力。此外,Imh1p二聚體(dimer)的能力也對於Imh1p穩定Arl1p的功能是很重要的。因此,在本篇論文證明了Imh1p參與了Gcs1p於時間、空間上所調控Arl1p的鳥糞嘌呤核苷三磷酸循環。 ARF-like proteins (ARLs) are one of the ADP-ribosylation factors (ARFs) family that are small GTP-binding proteins. Arf proteins enhance the ADP-ribosyltransferase activity of c0060holera toxin and have an important role in vesicular transport. Several ARLs have been cloned from different organisms. However, the biological functions of ARLs and its interacting protiens remain largely unknown. Recently, we have shown that Syt1p function as a GEF that promotes activation of Arl1p and recruitment of a golgin protein, Imh1p, to the Golgi. Gcs1p hydrolyzes GTP of Arl1p to inactivate Arl1p at later stage. Although mammalian golgins are proposed to regulate structure and function of the TGN, the physiological function of Imh1p remains not clear. Here, we report that Imh1p has a role on modulating inactivation of Arl1p on the Golgi. Deletion of IMH1 decreases the level of GTP-bound form Arl1p resulting in less amounts of Arl1p resided on TGN. Imh1p competes with Gcs1p in interacting with Arl1p and decreases Gcs1p GAP activity on Arl1p in vitro. Furthermore, the dimerization of Imh1p is necessary for its function on Arl1p. Our findings demonstrate that Imh1p participates in regulating Gcs1p-depndent spatial and temporal control of the GTP hydrolysis cycle of Arl1p. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/29208 |
全文授權: | 有償授權 |
顯示於系所單位: | 分子醫學研究所 |
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