Knudsen K A, Soler A P, Johnson K R, Wheelock M J
Lankenau Medical Research Center, Wynnewood, Pennsylvania 19096, USA.
J Cell Biol. 1995 Jul;130(1):67-77. doi: 10.1083/jcb.130.1.67.
Cadherins are Ca(2+)-dependent, cell surface glycoproteins involved in cell-cell adhesion. Extracellularly, transmembrane cadherins such as E-, P-, and N-cadherin self-associate, while intracellularly they interact indirectly with the actin-based cytoskeleton. Several intracellular proteins termed catenins, including alpha-catenin, beta-catenin, and plakoglobin, are tightly associated with these cadherins and serve to link them to the cytoskeleton. Here, we present evidence that in fibroblasts alpha-actinin, but not vinculin, colocalizes extensively with the N-cadherin/catenin complex. This is in contrast to epithelial cells where both cytoskeletal proteins colocalize extensively with E-cadherin and catenins. We further show that alpha-actinin, but not vinculin, coimmunoprecipitates specifically with alpha- and beta-catenin from N- and E-cadherin-expressing cells, but only if alpha-catenin is present. Moreover, we show that alpha-actinin coimmunoprecipitates with the N-cadherin/catenin complex in an actin-independent manner. We therefore propose that cadherin/catenin complexes are linked to the actin cytoskeleton via a direct association between alpha-actinin and alpha-catenin.
钙黏蛋白是一种依赖钙离子的细胞表面糖蛋白，参与细胞间黏附。在细胞外，跨膜钙黏蛋白如E-钙黏蛋白、P-钙黏蛋白和N-钙黏蛋白会自我缔合，而在细胞内，它们与基于肌动蛋白的细胞骨架间接相互作用。几种被称为连环蛋白的细胞内蛋白，包括α-连环蛋白、β-连环蛋白和桥粒斑珠蛋白，与这些钙黏蛋白紧密相连，并将它们与细胞骨架连接起来。在此，我们提供证据表明，在成纤维细胞中，α-辅肌动蛋白而非纽蛋白与N-钙黏蛋白/连环蛋白复合物广泛共定位。这与上皮细胞不同，在上皮细胞中，这两种细胞骨架蛋白都与E-钙黏蛋白和连环蛋白广泛共定位。我们进一步表明，α-辅肌动蛋白而非纽蛋白能从表达N-钙黏蛋白和E-钙黏蛋白的细胞中与α-连环蛋白和β-连环蛋白特异性地共同免疫沉淀，但前提是存在α-连环蛋白。此外，我们表明α-辅肌动蛋白与N-钙黏蛋白/连环蛋白复合物以肌动蛋白非依赖的方式共同免疫沉淀。因此，我们提出钙黏蛋白/连环蛋白复合物通过α-辅肌动蛋白与α-连环蛋白之间的直接结合与肌动蛋白细胞骨架相连。
