研究顯示，生物細胞膜上存在著異質性的結構。細胞膜上的這些脂質區塊，又稱作脂質浮排（lipid rafts），富含膽固醇及抱合脂質。這些區塊具有不同的化學成分及物理性質，其分子的有序程度也不同。一般認為，脂質浮排區域是處在較有序的液晶相(lo)，非脂質浮排區則是處在較無序的液晶相(ld)。脂質浮排被證明和許多重要的細胞過程有關，包括信號傳遞、蛋白質和脂質的分類、毒素和病毒的入侵、以及病毒的生成。由於脂質浮排對細胞功能的影響甚鉅，脂質浮排在細胞膜中如何形成的相關課題十分重要。而人造細胞膜的研究對於瞭解脂質浮排的物理性質及形成機制非常重要。在這個計畫中我們將觀察含脂質及固醇的人造細胞膜，我們將研究(i)在固醇含量極高的情況下，脂質/固醇人造細胞膜中的脂質碳氫鏈的有序程度隨著固醇的增加的變化，以及(ii) 當脂質/固醇人造細胞膜處於兩種液相共存態時，細胞膜的形態。另外，(iii)我們將研究模擬酵母菌脂質浮排成分的人造細胞膜，建立此人造細胞膜的相圖，並觀察此人造細胞膜的形態。(iv) 我們將觀察膜蛋白Pmp1P 對上述人造細胞膜的相行為的影響，並確定Pmp1P 與非脂質浮排區域的關聯性。我們將運用固態氘核磁共振(2H NMR)、原子力顯微術(AFM)、以及螢光顯/共軛焦微術的來研究上述的問題。 It is now widely accepted that lateral heterogeneities exist in biological membranes of living cell. Lipid domains enriched in cholesterol and sphingolipid, called lipid rafts, exist in cell membranes. These domains possess distinct lipid/protein compositions, degrees of order, and physical properties. The raft and non-raft regions are thought to be in the liquid-ordered (lo) and liquid-disordered phases, respectively. Lipid rafts have been shown to be involved in a wide range of important cellular processes, including signal transduction, protein and lipid sorting, cellular entry by toxins and viruses, and viral budding. As these raft domains can strongly affect cell functions, the organization of membranes into domains is of great interest. The studies of model membrane have been the key to understand the physical properties and the formation of lipid rafts. Binary or ternary mixture composed of lipid(s) and sterol will be used to study the properties of raft membranes. We propose to investigate (i) the dependence of membrane properties, in particular, the lipid chain order, on sterol concentration in lipid/sterol membranes for sterol concentration up to 80mol%, and (ii) the morphology of saturated lipid/sterol membranes in liquid-ordered (lo) and liquid-disordered (ld) phase coexistence. (iii) The phase diagram of model membranes mimicking rafts composition of yeast membranes will be constructed and the morphology of the membranes will be observed. (iv) We will investigate the effect of membrane protein Pmp1P on the phase behavior of model membranes mimicking rafts composition of yeast membranes and confirm whether Pmp1P is associated with non-raft region. 2H NMR spectroscopy, liquid atomic force microscopy (AFM), and fluorescence/confocal microscopy will used to investigate the above questions. 研究期間：9908 ~ 10007
