上海士锋生物关于转运蛋白家族双重作用的介绍

研究人员发现，在根部ZIFL1编码的蛋白对生长素运输至关重要，是植物生长和发育*的激素。然而，在叶片中，ZIFL1编码的蛋白能促进植物耐旱性。

这项研究中的基因能编码两种蛋白且发挥不同生物学功能，实属少数。ZIFL1属于转运蛋白家族基因，存在于所有生物类别。但多数家族成员的功能尚不清楚。目前已知的是转运基因编码的蛋白能整合至细胞膜，并允许小分子通过他们。

通过对模式植物拟南芥进行遗传和细胞生物学研究， Paula Duque的研究团队对ZIFL1基因的功能进行分析。让科学吃惊的是，无法产生ZIFL1转运蛋白的突变植物不同的器官和功能呈现特异缺陷。一方面，与正常植物相比，他们的根生长、分枝、取向出现问题。

总之，通过确定两个异构体亚细胞和组织分布，选择性剪切确定了ZIFL1转运蛋白的双重作用。

原文摘要：

A Major Facilitator Superfamily Transporter Plays a Dual Role in Polar Auxin Transport and Drought Stress Tolerance in Arabidopsis

Many key aspects of plant development are regulated by the polarized transport of the phytohormone auxin. Cellular auxin efflux, the rate-limiting step in this process, has been shown to rely on the coordinated action of PIN-formed （PIN） and B-type ATP binding cassette （ABCB） carriers. Here, we report that polar auxin transport in the Arabidopsis thaliana root also requires the action of a Major Facilitator Superfamily （MFS） transporter, Zinc-Induced Facilitator-Like 1 （ZIFL1）. Sequencing, promoter-reporter, and fluorescent protein fusion experiments indicate that the full-length ZIFL1.1 protein and a truncated splice isoform, ZIFL1.3, localize to the tonoplast of root cells and the plasma membrane of leaf stomatal guard cells, respectively. Using reverse genetics, we show that the ZIFL1.1 transporter regulates various root auxin-related processes, while the ZIFL1.3 isoform mediates drought tolerance by regulating stomatal closure. Auxin transport and immunolocalization assays demonstrate that ZIFL1.1 indirectly modulates cellular auxin efflux during shootward auxin transport at the root tip, likely by regulating plasma membrane PIN2 abundance. Finally, heterologous expression in yeast revealed that ZIFL1.1 and ZIFL1.3 share H+-coupled K+transport activity. Thus, by determining the subcellular and tissue distribution of two isoforms, alternative splicing dictates a dual function for the ZIFL1 transporter. We propose that this MFS carrier regulates stomatal movements and polar auxin transport by modulating potassium and proton fluxes in Arabidopsiscells.