Subcellular localization of the APC protein: immunoelectron microscopic study of the association of the APC protein with catenin.
Subcellular localization of the APC protein: immunoelectron microscopic study of the association of the APC protein with catenin.
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APC 蛋白的亚细胞定位：APC 蛋白与连环蛋白关联的免疫电子显微镜研究。
作者：
I. Miyashiro;T. Senda;Akihiko Matsumine;G. Baeg;Tadahiro Kuroda;T. Shimano;S. Miura;T. Noda;S. Kobayashi;M. Monden
APC基因突变与散发性结直肠肿瘤和家族性腺瘤性息肉病的发生有关。最近，APC蛋白被报道与连环蛋白相关，连环蛋白是与细胞粘附分子E-钙粘蛋白结合的蛋白。在本研究中，我们研究了APC蛋白和α-连环蛋白在正常小鼠肠道的分布和定位，通过光镜和免疫电镜使用特异性抗体。APC蛋白定位于微绒毛和上皮细胞的顶端和侧部细胞质中，而α-连环蛋白仅在侧部细胞质中检测到。双标记免疫电子显微镜显示APC蛋白与α-连环蛋白共定位在侧细胞质中，特别是沿着侧质膜，尽管该区域中的APC蛋白的某一部分独立于α-连环蛋白分布。这些结果表明，一部分APC蛋白定位在侧细胞质的肠上皮细胞的功能与连环蛋白的合作，而APC蛋白在微绒毛和顶端的细胞质有其他功能独立于连环蛋白。
Mutations in the APC gene are linked to the development of sporadic colorectal tumors as well as to familial adenomatous polyposis. Recently, the APC protein was reported to associated with catenins, proteins that bind to the cell adhesion molecule E-cadherin. In the present study, we examined the distribution and localization of the APC protein and alpha -catenin in the normal mouse intestine by light and immunoelectron microscopy using specific antibodies. The APC protein was found to be localized in microvilli and in the apical and lateral cytoplasm of the epithelial cells, whereas alpha-catenin was detected only in the lateral cytoplasm. Double-labeling immunoelectron microscopy showed colocalization of the APC protein with alpha-catenin in the lateral cytoplasm, especially along the lateral plasma membrane, although a certain portion of the APC protein in this region was distributed independently of alpha-catenin. These results suggest that a portion of the APC protein localized in the lateral cytoplasm of intestinal epithelial cells functions in cooperation with catenins, whereas the APC protein in microvilli and in the apical cytoplasm has other functions independent of catenins.