Intra-Golgi traffic

The mammalian Golgi consists of at least three biochemically distinct cisternae, cis-, medial- and trans (reviewed in Szul and Sztul, 2011; Day et al, 2013). The structure and function of the Golgi are tightly interconnected, such that proteins that are required for protein transport through the Golgi are often also required for the organization of the Golgi stacks, and vice versa (reviewed in Liu and Storrie, 2012; Liu and Storrie, 2015; Chia and Gleeson, 2014; Munro, 2011). Newly synthesized proteins from the ER and ERGIC are received at the cis face of the Golgi and flow through to the trans-Golgi before being released to the trans-Golgi network (TGN) for further secretion to the endolysosomal system, plasma membrane or extracellular region. Retrograde flow from the trans- to cis-cisternae moves endocytosed cargo from the extracellular region, the plasma membrane and the endolysosomal system back towards the ER. Intra-Golgi retrograde traffic also returns resident Golgi proteins to their appropriate cisternae, in this way facilitating cisternal remodeling or maturation (reviewed in Boncompain and Perez, 2013; Day et al, 2013). Intra-Golgi traffic in both directions is mediated by COPI carriers, with specificity of transport being determined at least in part by the complement of SNAREs, RABs and tethering proteins involved (reviewed in Szul and Sztul, 2011; Spang 2013; Willet et al, 2013; Chia and Gleeson, 2014).

哺乳动物的高尔基体至少由三个在生化上各异的囊腔组成，包括顺式、中位和反式囊腔（参见Szul和Sztul，2011年；Day等人，2013年）。高尔基体的结构与功能紧密相连，所需通过高尔基体进行蛋白质运输的蛋白质往往也参与高尔基体堆叠的组织，反之亦然（参见Liu和Storrie，2012年；Liu和Storrie，2015年；Chia和Gleeson，2014年；Munro，2011年）。从内质网和ERGIC新合成的蛋白质到达高尔基体的顺式面，并在到达反式高尔基面之前流动，随后被释放至反式高尔基网络（TGN），以便进一步分泌至内吞溶酶体系统、质膜或细胞外区域。从反式囊腔至顺式囊腔的反向流动将内吞的货物从细胞外区域、质膜和内吞溶酶体系统运回内质网。高尔基体内的双向交通由COPI载体介导，运输的特异性至少部分由参与的SNAREs、RABs和连接蛋白的组成决定（参见Szul和Sztul，2011年；Spang，2013年；Willet等人，2013年；Chia和Gleeson，2014年）。