College of Horticulture and Forestry Science, Hubei Engineering Technology Research Center for Forestry Information, Huazhong Agricultural University, Wuhan 430070, China.
Int J Mol Sci. 2018 Sep 14;19(9):2759. doi: 10.3390/ijms19092759.
Auxin plays crucial roles in multiple developmental processes, such as embryogenesis, organogenesis, cell determination and division, as well as tropic responses. These processes are finely coordinated by the auxin, which requires the polar distribution of auxin within tissues and cells. The intercellular directionality of auxin flow is closely related to the asymmetric subcellular location of PIN-FORMED (PIN) auxin efflux transporters. All PIN proteins have a conserved structure with a central hydrophilic loop domain, which harbors several phosphosites targeted by a set of protein kinases. The activities of PIN proteins are finely regulated by diverse endogenous and exogenous stimuli at multiple layers-including transcriptional and epigenetic levels, post-transcriptional modifications, subcellular trafficking, as well as PINs' recycling and turnover-to facilitate the developmental processes in an auxin gradient-dependent manner. Here, the recent advances in the structure, evolution, regulation and functions of PIN proteins in plants will be discussed. The information provided by this review will shed new light on the asymmetric auxin-distribution-dependent development processes mediated by PIN transporters in plants.
生长素在多个发育过程中发挥着关键作用，如胚胎发生、器官发生、细胞决定和分裂以及向性反应。这些过程由生长素精细协调，生长素需要在组织和细胞内极性分布。生长素流的细胞间方向性与 PIN 形成素（PIN）生长素外排转运蛋白的不对称亚细胞定位密切相关。所有 PIN 蛋白都具有保守的结构，具有中央亲水环域，其中包含几个磷酸化位点，这些磷酸化位点是一组蛋白激酶的靶标。PIN 蛋白的活性受多种内源性和外源性刺激的精细调节，包括转录和表观遗传水平、转录后修饰、亚细胞运输以及 PIN 的回收和周转，以促进依赖生长素梯度的发育过程。在这里，将讨论植物中 PIN 蛋白的结构、进化、调控和功能的最新进展。本综述提供的信息将为植物中由 PIN 转运蛋白介导的不对称生长素分布依赖的发育过程提供新的认识。
