膜脂质构成对淋巴细胞膜特性及膜蛋白结构与功能的影响

Influence of plasma membrane lipid composition on membrane properties and the conformation and function of membrane protein in lymphocyte

本实验通过人为改变淋巴细胞胞膜脂质构成，进而研究了膜脂质，尤其是膜胆固醇，对淋巴细胞膜生物物理特性及膜蛋白结构，以及Ｃａ２＋通道蛋白活性的影响。结果显示，随着胞膜磷脂（ＰＬ）／胆固醇（Ｃｈ）摩尔比的降低，膜脂质的微粘滞性升高，活化淋巴细胞超极化反应增强，胞浆游离钙浓度［Ｃａ２＋］ｉ及Ｃａ２＋跨膜流动增加，且上述膜电位及Ｃａ２＋内流的变化可因Ｃａ２＋通道受阻而减弱或消失。提示膜脂质可通过调节Ｃａ２＋通道蛋白活性，进而影响Ｃａ２＋跨膜内流及膜电位。另外，膜脂质组成改变后，膜蛋白内源性荧光强度及最大发射波长峰位的变化，也表明膜脂质及相关膜特性可影响膜蛋白的结构与功能。

The influences of plasma lipid composition on membrane properties, Ca 2+ channel activity, and the conformation of membrane protein were determined in lymphocyte. It was shown that the microviscosity of plasma membrane was increased with a decrease in phospholipid/cholesterol(PL/Ch) ratios in lymphocytes after treatment with small unilaminar vesicles(SUV) composed of various phosphatidylcholine/Ch. ConA or TPA stimulation initiated a decrease of microviscosity and hyperpolarized reaction in lymphocyte, as well as simultaneous increases in plasma free Ca 2+ concentration and Ca 2+ transportation across membrane. Membrane potential changes and altered Ca 2+ influx or efflux could be abolished by blocking Ca 2+ channel activity. Modification of membrane lipids seems to directly affect the conformation of Ca 2+ channel protein and further regulate Ca 2+ influx and membrane potential. Additionally, intrinsic fluorescence analysis of membrane proteins also suggests the possible involvement of membrane in the activation and signal transmission of lymphocyte by affecting the construction and function of protein.