叶绿体作为植物及藻类细胞中含有内外双层被膜的细胞器，能够通过光合作用过程将光能转化为化学能。大部分的叶绿体蛋白由细胞核基因编码，其前体蛋白是在细胞质中的80S核糖体上合成的。前体蛋白在转运肽的引导下，通过跨越叶绿体外被膜和内被膜的路径被传送进入叶绿体内部，进而到达发挥其生物学功能的目的微区。目前已知的前体蛋白转运的一个主要途径是通过叶绿体外被膜转运子(translocon in the outer envelope membrane of chloroplast，TOC)和内被膜转运子(translocon in the inner envelope membrane of chloroplast，TIC)，在二者的协同作用下前体蛋白得以跨越双层被膜进入叶绿体。文章回顾了TOC-TIC超复合物的结构生物学研究进展，并深入探讨了各组件的功能特性以及前体蛋白易位至叶绿体内部的潜在途径和调控机制。
Components and structural mechanism of the chloroplast protein translocon TOC-TIC supercomplex
Chloroplasts,the special organelles present in plant and algal cells,are responsible for converting light energy into chemical energy through photosynthesis.The majority of chloroplast proteins are encoded by nuclear genes.And the precursor proteins(preproteins)are synthesized by the 80S ribosomes in cytosol.Subsequently,guided by the transit peptides,preproteins are delivered into the chloroplasts through the post-translational translocation pathways across the outer and inner envelop membranes to fulfill their biological functions inside the chloroplasts.The central route for the preproteins to enter the chloroplast mainly relies on the synergistic action of the translocons in the outer and inner envelope membranes of chloroplasts(TOC and TIC).Here we review the recent research progress on structural biology studies of the TOC-TIC supercomplex and discuss the functional characteristics of its components,potential pathways for precursor protein translocation into chloroplasts,and the regulatory mechanisms.
万方数据
维普
