Drenckhahn D, Franz H
J Cell Biol. 1986 May;102(5):1843-52. doi: 10.1083/jcb.102.5.1843.
In this paper, a new type of spot desmosome-like junction (type II plaque) is described that is scattered along the entire lateral plasma membrane of rat and human intestinal epithelium. Ultrastructurally type II plaques differed from the classical type of epithelial spot desmosome ("macula adherens", further denoted as type I desmosome) by weak electron density of the membrane-associated plaque material, association of the plaques with microfilaments rather than intermediate filaments, and poorly visible material across the intercellular space. Thus, type II plaques resemble cross-sections of the zonula adherens. Immunofluorescence-microscopic studies were done using antibodies to a main protein associated with the plaques of type I desmosomes (desmoplakin I) and to the three major proteins located at the plaques of the zonula adherens (actin, alpha-actinin, and vinculin). Two types of plaques were visualized along the lateral surface of intestinal and prostatic epithelium: (a) the type I desmosomes, which were labeled with anti-desmoplakin but did not bind antibodies to actin, alpha-actinin, and vinculin, and (b) a further set of similarly sized plaques, which bound antibodies to actin, alpha-actinin, and vinculin but were not stained with anti-desmoplakin. Three-dimensional computer reconstruction of serial sections double-labeled with anti-desmoplakin and anti-alpha-actinin further confirmed that both types of plaques are spatially completely separated from each other along the lateral plasma membrane. The computer graphs further revealed that the actin-, alpha-actinin-, and vinculin-containing plaques have the tendency to form clusters, a feature also typical of type II plaques. It is suggested that the type II plaques represent spot desmosome-like intercellular junctions, which, like the zonula adherens, appear to be linked to the actin filament system. As the type II plaques cover a considerable part of the lateral cell surface, they might play a particular role in controlling cellular shape and intercellular adhesion.
在本文中，描述了一种新型的点状桥粒样连接（II型斑块），其沿大鼠和人类肠上皮细胞的整个外侧质膜分散分布。超微结构上，II型斑块与经典的上皮点状桥粒（“黏着斑”，进一步称为I型桥粒）不同，其膜相关斑块物质的电子密度较弱，斑块与微丝而非中间丝相关联，并且细胞间空间中的物质难以看清。因此，II型斑块类似于黏着带的横截面。使用针对与I型桥粒斑块相关的主要蛋白质（桥粒斑蛋白I）以及位于黏着带斑块处的三种主要蛋白质（肌动蛋白、α-辅肌动蛋白和纽蛋白）的抗体进行了免疫荧光显微镜研究。在肠和前列腺上皮细胞的外侧表面观察到两种类型的斑块：（a）I型桥粒，用抗桥粒斑蛋白标记，但不结合抗肌动蛋白、抗α-辅肌动蛋白和抗纽蛋白的抗体；（b）另一组大小相似的斑块，结合抗肌动蛋白、抗α-辅肌动蛋白和抗纽蛋白的抗体，但不被抗桥粒斑蛋白染色。用抗桥粒斑蛋白和抗α-辅肌动蛋白双重标记的连续切片的三维计算机重建进一步证实，两种类型的斑块在外侧质膜上在空间上彼此完全分离。计算机图形还显示，含有肌动蛋白、α-辅肌动蛋白和纽蛋白的斑块有形成簇的倾向，这也是II型斑块的典型特征。有人提出，II型斑块代表点状桥粒样细胞间连接，与黏着带一样，似乎与肌动蛋白丝系统相连。由于II型斑块覆盖了细胞外侧表面的相当一部分，它们可能在控制细胞形状和细胞间黏附中起特殊作用。
