The Function of HASTY in Arabidopsis

分子在核膜上的转运主要是由输入蛋白家族成员调控的。虽然这些蛋白的功能在酵母和哺乳动物中被很好地表征，但它们在植物中的功能却知之甚少。本项目描述的实验旨在揭示Exportin5的拟南芥同源基因HASTY的功能。Exportin5在哺乳动物中与mirna和trna的核输出有关，而hasty的突变表型表明它可能在植物中具有类似的功能。这一假设将通过检查仓促突变对mirna和trna亚细胞分布的影响，以及通过鉴定仓促蛋白在体内和体外物理相互作用的分子来验证。筛选抑制HST -3表型的突变，以确定与HST功能相关的基因。定位克隆将用于鉴定受这种突变soh影响的基因，并对其功能进行表征。目前，在存在突变等位基因的高等生物中，HASTY是唯一与Exportin5同源基因。这些突变为研究这种重要蛋白的功能提供了一个独特的机会，也可能为mirna的生物发生和功能提供新的见解。

The transport of molecules across the nuclear membrane is primarily regulated by members of the importin beta family of proteins. Although the function of these proteins is well characterized in yeast and mammals, very little is known about their function in plants. The experiments described in this project are designed to reveal the function of HASTY, the Arabidopsis orthologue of Exportin5. Exportin5 has been implicated in the nuclear export of miRNAs and tRNAs in mammals, and the mutant phenotype of hasty suggests that it may have a similar function in plants. This hypothesis will be tested by examining the effect of hasty mutations on the sub-cellular distribution of miRNAs and tRNAs, and by identifying the molecules with which the HASTY protein physically interacts in vivo and in vitro. Screens for mutations that suppress the phenotype of hst-3 have been conducted in order to identify genes that are functionally related to HST. Positional cloning will be used to identify the gene affected by one such mutation, soh, and its function will be characterized. At present, HASTY is the only orthologue of Exportin5 in higher organisms for which mutant alleles exist. These mutations provide a unique opportunity to study the function of this important protein, and may provide new insights into the biogenesis and function of miRNAs as well.