许多细胞功能依赖于细胞内液游离钙离子浓度的变化。细胞内液钙离子浓度的增加有两种基本途径:一条是从细胞内钙离子贮存部位释放出来:另一条是钙离子通过膜从细胞外进入细胞内。控制第二条途径最重要的结构是镶嵌在细胞膜脂质双层内的蛋白质,它作为“通道”或“孔道”而发挥作用,有了它钙离子才能流动。这些通道的分 Many cellular functions depend on changes in intracellular free calcium concentration. There are two basic ways to increase the intracellular calcium concentration: one is released from the intracellular calcium stores; the other is calcium ions that enter the cell from outside the cell through the membrane. The most important structure that controls the second pathway is the protein embedded in the lipid bilayer of the cell membrane, which functions as a “channel” or “pore” that allows calcium ions to flow. Points for these channels