Döbereiner H G, Käs J, Noppl D, Sprenger I, Sackmann E
Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada.
Biophys J. 1993 Oct;65(4):1396-403. doi: 10.1016/S0006-3495(93)81203-7.
We report on budding and fission of protein-free vesicles swollen from a natural lipid mixture of bovine brain sphingomyelins. Budding was induced by increasing the area-to-volume ratio through heating. Morphological changes were monitored by phase contrast microscopy and correlated with the thermal behavior of the bilayer by differential scanning calorimetry. Freeze fracture electron microscopy revealed that budding and fission are not restricted to giant vesicles but also occur on length scales relevant for cellular processes. We also observed osmotically induced budding and fission in mixtures of dimyristoyl phosphatidylcholine with cholesterol. We find that these shape transitions are driven by liquid/gel domain formation and/or coupling of the spontaneous curvature of the membrane to the local lipid composition. Our results provide evidence that coat proteins are not necessary for budding and fission of vesicles. The physics of the lipid bilayer is rich enough to explain the observed behavior.
我们报道了由牛脑鞘磷脂的天然脂质混合物膨胀形成的无蛋白囊泡的出芽和裂变。通过加热增加面积与体积比可诱导出芽。通过相差显微镜监测形态变化，并通过差示扫描量热法将其与双层膜的热行为相关联。冷冻断裂电子显微镜显示，出芽和裂变不仅限于巨型囊泡，也发生在与细胞过程相关的长度尺度上。我们还观察到在二肉豆蔻酰磷脂酰胆碱与胆固醇的混合物中渗透诱导的出芽和裂变。我们发现这些形状转变是由液/凝胶域的形成和/或膜的自发曲率与局部脂质组成的耦合驱动的。我们的结果提供了证据，表明囊泡的出芽和裂变不需要包被蛋白。脂质双层的物理性质足以解释观察到的行为。
