Vesicle formation and recycling in the secretory pathway - from yeast to higher plants

酵母研究：1)分析了3个Arf1 GTPase等位基因，分离出多拷贝抑制基因。我们认为不同的gef和gap以等位基因特异性的方式参与。2)我们证明了Rer1p是高尔基体中检索ER膜蛋白子集的分选受体。我们还鉴定了Rer1p的高尔基定位信号，并表明它们与COPI组分相互作用。3)我们确定了Sec12p和Sec71p的er定位信号。我们还结晶了Sec12p并分析了它的三维结构。4)我们发现麦角甾醇对于色氨酸渗透酶Tat2p靶向质膜至关重要。5)我们证明了Rer2p及其同源物Srt1p都具有顺式戊烯基转移酶活性，但表现出不同的特征。植物方面的研究：1)将AtARF1显性负突变体导入植物细胞，发现其表达抑制er -高尔基转运。2)我们确定了Ara6和Ara7是Rab GTPase家族的新成员，并表明它们在内体中起作用。我们发现Ara6具有不同于其他传统Rab GTPases的独特特征。3)我们发现，最初作为酵母sec15突变体抑制因子分离的拟南芥RMA1编码一种新的膜结合泛素连接酶。4)利用γ - tip - gfp对拟南芥液泡膜进行了观察，发现液泡膜的结构是动态的、复杂的。5)通过对拟南芥茎部向地性突变体的分析，证明液泡生物发生在重力感知中起着重要作用。

Studies on yeast :1) We analyzed ts alleles of Arf1 GTPase and isolated multicopy suppressors. We suggested that different GEFs and GAPs are involved in an allele-specific manner. 2) We demonstrated that Rer1p is a sorting receptor in the Golgi that retrieves a subset of ER membrane proteins. We also identified the Golgi-localization signals of Rer1p and showed that they interact with COPI components. 3) We identified ER-localization signals of Sec12p and Sec71p. We also crystalized Sec12p and analyzed its 3-D structure. 4) We showed that ergosterol is essential for targeting of the tryptophan permease Tat2p to the plasma membrane. 5) We demonstrated that both Rer2p and its homologue Srt1p have the cis-prenyltransferase activity but show different characteristics.Studies on plants :1) We introduced dominant negative mutants of AtARF1 into plant cells and showed that its expression inhibits ER-Golgi traffic. 2) We identified Ara6 and Ara7 as new members of the Rab GTPase family and showed that they function in endosomes. We showed that Ara6 has uniques features distinct from other conventional Rab GTPases. 3) We showed that Arabidopsis RMA1, originally isolated as a suppressor of the yeast sec15 mutant, encodes a novel membrane-bound ubiquitin ligase. 4) We showed that vacuole membranes of Arabidopsis plants as visualized by γTIP-GFP display very dynamic and complex structures. 5) We demonstrated from the analysis of Arabidopsis shoot gravitropism mutants that vacuole biogenesis plays very important roles in the sensing of the gravity.