Structural Studies of Sugar Transporters

膜转运，例如葡萄糖的摄取，对细胞是必不可少的.这种过程往往是通过调解 通过二级膜转运蛋白。最大的次级转运蛋白家族是主要的促进剂 MFS是一个葡萄糖转运蛋白超家族（MFS），迄今已鉴定出5,000多个成员，包括来自 肌肉（Glut 4）和葡萄糖-6-磷酸转运蛋白（G6 PT），两者都来自人类，都参与了 2型糖尿病的发病机制。我们建议研究细菌同源物的转运机制 Glut 4和G6 PT的同源性分别为1.0%和1.0%。大肠杆菌，利用结构生物学， 生物化学和光谱方法。在上一个融资周期中，我们确定了晶体 以3.3 A分辨率显示无底物形式的GIpT结构。结构建议一个“摇杆开关” 用于基板传输的机构。在下一个融资周期中，为了更好地了解GIpT的底物， 特异性和底物诱导的构象变化，我们计划确定 两种底物结合形式的转运蛋白。我们还将测试摇杆开关机制，并检查 关键氨基酸残基的作用，使用诱变，转运测定和光谱技术。 从GIpT中获得的结构和机理信息可以直接用于改进我们的 Glut 4和G6 PT。

Membrane transport, for example glucose uptake, Is essential to the cell. Such processes are often mediated by secondary membrane transporters. The largest secondary transporter family is the major facilitator superfamily (MFS), with more than 5,000 members identified to date, including the glucose transporter from muscle (Glut4) and the glucose-6-phosphate transporter (G6PT), both from human and both are involved in the pathogenesis of type 2 diabetes. We propose to study the transport mechanisms of a bacterial homolog of Glut4 and G6PT, the glycerol-3-phosphate transporter (GIpT) from E. coli, using structural biology, biochemistry and spectroscopic approaches. In the previous funding cycle, we determined the crystal structure of GIpT in a substrate-free form at 3.3 A resolution. The structure suggests a "rocker-switch" mechanism for substrate transport. In the next funding cycle, to better understand GIpT's substrate specificity and substrate-induced conformational change, we plan to determine the crystal structures of the transporter in two substrate-bound forms. We will also test the rocker-switch mechanism and examine the role that key amino acid residues play using mutagenesis, transport assays and spectroscopic techniques. The structural and mechanistic information gained from GIpT can be used directly to improve our understanding of Glut4 and G6PT.