Citi S, Sabanay H, Jakes R, Geiger B, Kendrick-Jones J
MRC Laboratory of Molecular Biology, Cambridge, UK.
Nature. 1988 May 19;333(6170):272-6. doi: 10.1038/333272a0.
The tight junction (Zonula occludens), a belt-like region of contact between cells of polarized epithelia, serves as a selective barrier to small molecules and as a total barrier to large molecules, and is involved in the separation between lumenal and basolateral compartments of the epithelium. In the electron microscope, tight junctions show focal regions of apparent fusion between the adjoining cell membranes, and freeze-fractured membranes display an elaborate network of branching and anastomosing strands. Very little is known about the molecular composition and architecture of tight junctions. The first specific zonula occludens-associated protein, designated ZO-1, has recently been identified in mammalian epithelial and endothelial cells. Here we describe the identification and purification of a new component of this junctional complex in avian brush-border cells, which we name cingulin. Cingulin is an acidic, heat-stable protein, with a highly elongated shape. Immunofluorescence and immunoelectron microscopy of brush-border cells with anti-cingulin antibodies show that cingulin is localized in the apical zone of the terminal web, at the endofacial surfaces of the zonula occludens.
紧密连接（闭锁小带）是极化上皮细胞间呈带状的接触区域，对小分子起选择性屏障作用，对大分子起完全屏障作用，并参与上皮细胞腔面和基底外侧区室的分隔。在电子显微镜下，紧密连接显示相邻细胞膜之间明显融合的局部区域，经冷冻断裂的细胞膜呈现出一个由分支和吻合链组成的精细网络。人们对紧密连接的分子组成和结构了解甚少。最近在哺乳动物上皮细胞和内皮细胞中鉴定出了首个特定的闭锁小带相关蛋白，命名为ZO-1。在此我们描述了在禽刷状缘细胞中该连接复合体一个新组分的鉴定和纯化过程，我们将其命名为cingulin。Cingulin是一种酸性、热稳定的蛋白质，形状高度细长。用抗cingulin抗体对刷状缘细胞进行免疫荧光和免疫电子显微镜观察表明，cingulin定位于终末网的顶端区域，即闭锁小带的内表面。
