细胞膜和细胞表面文件材料.pptVIP

cell-adhesion molecules (CAMs) 细胞黏连分子分成钙黏素，免疫球蛋白超家族，整合素，选择素。 其他参加细胞粘连的膜蛋白 A large number of CAMs fall into four major families: the cadherins, immunoglobulin (Ig) superfamily, integrins, and selectins. Some other membrane proteins, whose structures do not belong to any of the major classes of CAMs, also participate in cell–cell adhesion in various tissues. 相同粘连分子的连接称为同亲性homophilic binding，不同粘连分子连接称为异亲性heterophilic binding 细胞粘连可以是牢固的，如上皮细胞间的连接；也可以是微弱的，短暂的，如免疫细胞穿越血管内皮。 Cell–cell adhesions can be tight and long lasting or relatively weak and transient. The associations between nerve cells in the spinal cord or the metabolic cells in the liver exhibit tight adhesion. In contrast, immune-system cells in the blood can exhibit only weak, short-lasting interactions, allowing them to roll along and pass through a blood vessel wall on their way to fight an infection within a tissue. 细胞粘连分子先形成二聚体或寡聚体，这种作用是细胞内的，然后在不同细胞间粘连分子相互连接，这种作用是细胞间的，后者能促进细胞内的聚合。 First, CAMs on one cell associate laterally through their extracellular domains or cytosolic domains or both into homodimers or higher-order oligomers in the plane of the cell’s plasma membrane; these interactions are called intracellular, lateral, or cis interactions. Second, CAM oligomers on one cell bind to the same or different CAMs on an adjacent cell; these interactions are called intercellular or trans interactions. Trans interactions sometimes induce additional cis interactions and, as a consequence, yet even more trans interactions. 上皮细胞间的连接和粘连分子Sheetlike Epithelial Tissues:Junctions and Adhesion Molecules 上皮细胞可分成游离面，基底面和侧面 the distinct surfaces of a polarized epithelial cell are called the apical (top), basal (base or bottom), and lateral (side) surfaces 3类连接，锚定，紧密，缝隙 锚定连接对应桥粒和中间链接，起绑定细胞作用，紧密连接封闭细胞间缝隙。缝隙连接在相邻细胞间扩散亲水性小分子。 Three major classes of animal cell junctions are prominent Anchoring junctions and tight junctions perform the key task of holding cells together into tissues. Tight junctions also control the flow