Molecular determinants specifying cellular polarity of ENHANCER OF PINOID

在类松素突变体背景下，拟南芥基因ENHANCER OF PINENI（ENP）的突变导致表皮中生长素转运蛋白PINI的极性完全逆转。生长素运输受到干扰导致胚缺乏子叶。在成年阶段，植物的茎没有花。我们的工作表明，ENP，一个同系物的向光因子NPH 3，是精确的共定位与PINI。然而，ENP是一种具有可溶性蛋白质特征的蛋白质，其到达目的地的方式与跨膜蛋白PINI不同。我们的初步工作表明，ENP的BTB/POZ结构域是其极性定位所必需的，而C-末端区域可能具有PINI极性和/或生长素运输的功能。ENP显然是表皮细胞极性所需的关键因素。然而，介导其自身极性的分子机制仍然难以捉摸。了解ENP极性和功能的一个主要关键在于它与其他细胞成分的相互作用。因此，本申请提出了一系列的实验，研究ENP的细胞动力学，其领域的意义，以及通过先进的手段分析相互作用。

Mutation of the Arabidopsis thaliana gene ENHANCER OF PINOID (ENP) in pinoid mutant background leads to complete reversal of the polarity of the auxin transporter PINI in the epidermis. The disturbed auxin transport leads to embryos lacking cotyledons. In adult stages, plants with blind-ending stems lacking flowers develop. Our work has revealed that ENP, a homolog of the phototropic factor NPH3, is precisely co-localized with PINI. However, ENP, a protein with characteristics of soluble proteins, reaches its destination on a different way than PINI, a transmembrane protein. Our preliminary work shows, that the BTB/POZ domain of ENP is required for its polar localization whereas the C-terminal regions likely harbour functionality for PINI polarity and/or auxin transport. ENP is obviously a crucial factor required for epidermal cell polarity. However, the molecular mechanisms, which mediate its own polarity remain elusive. A major key to understand ENP polarity and function lies in its interactions with other cellular elements. Therefore, this application proposes a series of experiments, which investigate the cellular dynamics of ENP, the significance of its domains as well as the analysis of interactors by advanced means.