Wheeler T J, Hinkle P C
Annu Rev Physiol. 1985;47:503-17. doi: 10.1146/annurev.ph.47.030185.002443.
The glucose transporter is now identified but may have modifications or other subunits that control its activity. The kinetics and inhibitor binding studies are consistent with the carrier model with different degrees of asymmetry and a single binding site that varies in specificity depending on the conformation of the protein. The physical structure could actually be quite different from the usual diagrams (rocking bananas), however, and could function as a monomer or higher oligomer. The binding site, or filter, that gives specificity could be in the middle as usually depicted; alternatively it could be entirely on the cytoplasmic side, where the protein is trypsin sensitive, and hydrophobic helices could span the membrane forming a simple channel. Possible restrictions on structures in the membrane from the hydrophobic nature of transmembrane segments of membrane proteins (62) may favor a globular domain outside the membrane as the binding site. Such speculations will have to await more structural information about the transporter.
葡萄糖转运蛋白现已被识别，但可能存在控制其活性的修饰或其他亚基。动力学和抑制剂结合研究与具有不同程度不对称性和单一结合位点的载体模型一致，该结合位点的特异性根据蛋白质的构象而变化。然而，其物理结构实际上可能与通常的示意图（摇摆的香蕉）有很大不同，并且可以作为单体或更高聚体发挥作用。赋予特异性的结合位点或筛选器可能如通常所描绘的那样位于中间；或者它可能完全位于细胞质一侧，在该侧蛋白质对胰蛋白酶敏感，疏水螺旋可以跨越膜形成一个简单的通道。由于膜蛋白跨膜片段的疏水性质（62）对膜中结构的可能限制，可能有利于膜外的球状结构域作为结合位点。这些推测必须等待有关转运蛋白的更多结构信息。
