Glycophorin A Dimers to Probe Membranes: A 2D-IR Study

用2D-IR实验研究了跨膜的平衡结构和动力学 糖蛋白A(GPA)在几种脂质双层环境中的表达。血糖素A通过弱的二聚体 范德华作用力和CAH…O氢键。可以预料的是，这些弱联想很容易 随着环境的变化而中断。因此，2D-IR研究考察了 相反链上的残基将揭示GPA的结构如何随着 环境发生了变化。将研究几种脂质双层，包括二肉豆蔻酰磷脂酰胆碱(DMPC) 膜囊泡和DMPC/胆固醇囊泡，以探索脂质成分如何影响结构， 从而发挥跨膜蛋白的功能。这项工作将检验关于脂质作用的假说 蛋白质结构上的微域或“筏”。单频和双频2D-IR光子回波实验将 在不同的脂相中对同位素标记的GPA进行检测，以确定哪些相互作用最大 对环境敏感的。 跨膜蛋白不容易用传统技术探测，而且 膜成分对跨膜结构和功能的影响还不是很清楚。因为有很多人 对细胞功能至关重要的跨膜蛋白，了解膜环境之间的相互作用 而蛋白质结构是至关重要的。

2D-IR experiments are proposed to study the equilibrium structure and dynamics of the transmembrane protein Glycophorin A (GpA) in several lipid bilayer environments. Glycophorin A dimerizes through weak van der Waals forces and CaH...O hydrogen bonds. It is expected that these weak associations are easily disrupted as the environment is changed. Thus, 2D-IR studies examining the interactions between the residues on opposite strands will reveal information about how the structure of GpA changes as the environment changes. Several lipid bilayers will be studied, both a dimyristoylphosphatidylcholine (DMPC) membrane vesicle and a DMPC/cholesterol vesicle, to probe how lipid composition influences the structure, and thus function, of transmembrane protein. This work will test hypotheses about the role of lipid microdomains or "rafts" on protein structure. Single and Dual Frequency 2D-IR photon echo experiments will be performed on isotopically labeled GpA in different lipid phases to determine which interactions are most sensitive to environment. Transmembrane proteins are not easily probed by conventional techniques, and the influence of membrane composition on transmembrane structure and function is not well understood. Since many transmembrane proteins critical to cell function, understanding the interplay between membrane environment and protein structure is vitallv important.