Regulation of secretion, exocytosis and membrane fusion by vesicular lipids

细胞分泌的用于细胞间通讯的许多分子（如激素）被包装在细胞内的小泡中（每个小泡被含有大量胆固醇的脂质膜包围）。细胞中包装的信号分子的分泌涉及到囊泡与细胞表面的融合（细胞表面也被脂质膜包围，其胆固醇密度约为囊泡膜的1/3）；这个过程从一个非常小的孔的形成开始，这个孔连接着囊泡内部和细胞表面。

Many molecules (e.g. hormones) that are secreted by cells for communications between cells are packaged into small vesicles (each surrounded by a lipid membrane that includes lots of cholesterol) within the cell. The secretion of the packaged signaling molecules from a cell involves the fusion of the vesicle with the cell's surface (which is also surrounded by a lipid membrane whose density of cholesterol is about 1/3 that of the vesicular membrane); this process starts with the formation of a very small pore that connects the inside of a vesicle with the cell's surface.