Staddon J M, Smales C, Schulze C, Esch F S, Rubin L L
Eisai London Research Laboratories Ltd., University College London, United Kingdom.
J Cell Biol. 1995 Jul;130(2):369-81. doi: 10.1083/jcb.130.2.369.
Cadherins and catenins play an important role in cell-cell adhesion. Two of the catenins, beta and gamma, are members of a group of proteins that contains a repeating amino acid motif originally described for the Drosophila segment polarity gene armadillo. Another member of this group is a 120-kD protein termed p120, originally identified as a substrate of the tyrosine kinase pp60src. In this paper, we show that endothelial and epithelial cells express p120 and p100, a 100-kD, p120-related protein. Peptide sequencing of p100 establishes it as highly related to p120. p120 and p100 both appear associated with the cadherin/catenin complex, but independent p120/catenin and p100/catenin complexes can be isolated. This association is shown by coimmunoprecipitation of cadherins and catenins with an anti-p120/p100 antibody, and of p120/p100 with cadherin or catenin antibodies. Immunocytochemical analysis with a p120-specific antibody reveals junctional colocalization of p120 and beta-catenin in epithelial cells. Catenins and p120/p100 also colocalize in endothelial and epithelial cells in culture and in tissue sections. The cellular content of p120/p100 and beta-catenin is similar in MDCK cells, but only approximately 20% of the p120/p100 pool associates with the cadherin/catenin complex. Our data provide further evidence for interactions among the different arm proteins and suggest that p120/p100 may participate in regulating the function of cadherins and, thereby, other processes influenced by cell-cell adhesion.
钙黏蛋白和连环蛋白在细胞间黏附中发挥着重要作用。其中两种连环蛋白，β连环蛋白和γ连环蛋白，是一组蛋白质的成员，该组蛋白质含有最初在果蝇节段极性基因犰狳中描述的重复氨基酸基序。该组的另一个成员是一种称为p120的120-kD蛋白质，最初被鉴定为酪氨酸激酶pp60src的底物。在本文中，我们表明内皮细胞和上皮细胞表达p120和p100，一种100-kD的、与p120相关的蛋白质。p100的肽序列分析表明它与p120高度相关。p120和p100似乎都与钙黏蛋白/连环蛋白复合物相关，但可以分离出独立的p120/连环蛋白和p100/连环蛋白复合物。这种关联通过用抗p120/p100抗体对钙黏蛋白和连环蛋白进行共免疫沉淀，以及用钙黏蛋白或连环蛋白抗体对p120/p100进行共免疫沉淀来显示。用p120特异性抗体进行的免疫细胞化学分析揭示了上皮细胞中p120和β连环蛋白的连接共定位。连环蛋白和p120/p100在培养的内皮细胞和上皮细胞以及组织切片中也共定位。在MDCK细胞中，p120/p100和β连环蛋白的细胞含量相似，但只有约20%的p120/p100库与钙黏蛋白/连环蛋白复合物相关。我们的数据为不同犰狳蛋白之间的相互作用提供了进一步的证据，并表明p120/p100可能参与调节钙黏蛋白的功能，从而参与受细胞间黏附影响的其他过程。
