The major facilitator superfamily (MFS) represents the largest group of secondary active membrane transporters, and its members transport a diverse range of substrates. Recent work shows that MFS antiporters, and perhaps all members of the MFS, share the same three-dimensional structure, consisting of two domains that surround a substrate translocation pore. The advent of crystal structures of three MFS antiporters sheds light on their fundamental mechanism; they operate via a single binding site, alternating-access mechanism that involves a rocker-switch type movement of the two halves of the protein. In the sn-glycerol-3-phosphate transporter (GlpT) from Escherichia coli, the substrate-binding site is formed by several charged residues and a histidine that can be protonated. Salt-bridge formation and breakage are involved in the conformational changes of the protein during transport. In this review, we attempt to give an account of a set of mechanistic principles that characterize all MFS antiporters.

中文翻译：

---

主要促进者超家族反转运蛋白的来龙去脉。


主要促进子超家族 (MFS) 代表最大的次级活性膜转运蛋白群体，其成员转运多种底物。最近的研究表明，MFS 反向转运蛋白，或许还有 MFS 的所有成员，都具有相同的三维结构，由两个围绕底物易位孔的结构域组成。三种 MFS 反向转运蛋白晶体结构的出现揭示了它们的基本机制；它们通过单一结合位点、交替访问机制进行操作，该机制涉及蛋白质两半的摇杆开关式运动。在大肠杆菌的 sn-甘油-3-磷酸转运蛋白 (GlpT) 中，底物结合位点由几个带电残基和一个可质子化的组氨酸形成。盐桥的形成和断裂涉及蛋白质在运输过程中的构象变化。在这篇综述中，我们试图阐述一组表征所有 MFS 反向转运蛋白的机械原理。