Department of Chemistry and Biochemistry, University of California, San Diego 92093, USA.
Annu Rev Anal Chem (Palo Alto Calif). 2013;6:305-28. doi: 10.1146/annurev-anchem-062012-092631. Epub 2013 Apr 1.
Many biological membranes consist of 50% or more (by weight) membrane proteins, which constitute approximately one-third of all proteins expressed in biological organisms. Helical membrane proteins function as receptors, enzymes, and transporters, among other unique cellular roles. Additionally, most drugs have membrane proteins as their receptors, notably the superfamily of G protein-coupled receptors with seven transmembrane helices. Determining the structures of membrane proteins is a daunting task because of the effects of the membrane environment; specifically, it has been difficult to combine biologically compatible environments with the requirements for the established methods of structure determination. There is strong motivation to determine the structures in their native phospholipid bilayer environment so that perturbations from nonnatural lipids and phases do not have to be taken into account. At present, the only method that can work with proteins in liquid crystalline phospholipid bilayers is solid-state NMR spectroscopy.
许多生物膜由 50%或更多（按重量计）的膜蛋白组成，这些膜蛋白约占生物体内表达的所有蛋白质的三分之一。螺旋膜蛋白具有受体、酶和转运蛋白等独特的细胞功能。此外，大多数药物的受体都是膜蛋白，特别是具有七个跨膜螺旋的 G 蛋白偶联受体超家族。由于膜环境的影响，确定膜蛋白的结构是一项艰巨的任务；具体来说，很难将生物相容的环境与既定结构确定方法的要求结合起来。强烈希望在其天然磷脂双层环境中确定结构，以便不必考虑来自非天然脂质和相的干扰。目前，唯一可以在液晶磷脂双层中处理蛋白质的方法是固态 NMR 光谱学。
