Functional analysis of the SYP1 syntaxin family

合成素是靶膜上的受体，在细胞内运输中介导通路特异性囊泡对接。在拟南芥的24个推定合成素中，SYP1家族的9个成员与其他真核生物的质膜相关合成素表现出较弱的相似性。除了细胞分裂特异性合成素KNOLLE （SYP111）和质膜定位烟草SYR1 （SYP121）的推测同源物外，对SYP1蛋白一无所知。这个项目的目的是分析SYP1家族的所有成员。我们将寻找敲除突变体，并检查它们在细胞内运输中可能存在的缺陷。myc标记的SYP1蛋白的表达和亚细胞定位将在转基因植物中进行研究。myc标记的SYP1蛋白将在KNOLLE（和SYR1）顺式调控序列的控制下表达，以评估其针对细胞板（和质膜）的功能特异性以及交叉补体KNOLLE（和SYR1）突变体的能力。利用细胞周期调节的KNOLLE蛋白的积累、靶向和功能作为检测系统，我们旨在鉴定SYP1蛋白的功能域。为此，将分析由不同比例的KNOLLE和其他SYP1蛋白组成的嵌合蛋白的靶向性、稳定性和KNOLLE拯救活性。

Syntaxins are receptors on target membranes that mediate pathway-specific vesicle docking in intracellular trafficking. Among the 24 putative syntaxins of Arabidopsis, the 9 members of the SYP1 family display weak similarity to plasma membrane-associated syntaxins of other eukaryotes. Except for the cytokinesis-specific syntaxin KNOLLE (SYP111) and a putative orthologue of the plasma membrane-localised tobacco SYR1 (SYP121), nothing is known about SYP1 proteins. The aim of this project is to analyse all members of the SYP1 family. We will search for knockout mutants and examine their possible defects in intracellular trafficking. Expression and subcellular localisation of myc-tagged SYP1 proteins will be studied in transgenic plants. Myc-tagged SYP1 proteins will be expressed under the control of KNOLLE (and SYR1) cis-regulatory sequences to assess their functional specificity in terms of targeting to the cell plate (and plasma membrane) and ability to cross-complement knolle (and syr1) mutants. Using the cell cycle-regulated accumulation, targeting and function of KNOLLE protein as an assay system, we aim to identify functional domains of SYP1 proteins. To this end, chimaeric proteins consisting of varying proportions of KNOLLE and other SYP1 proteins will be analysed for targeting, stability and knolle rescuing activity.