The FAM deubiquitylating enzyme localizes to multiple points of protein trafficking in epithelia, where it associates with E-cadherin and beta-catenin.
Ubiquitylation is a necessary step in the endocytosis and lysosomal trafficking of many plasma membrane proteins and can also influence protein trafficking in the biosynthetic pathway. Although a molecular understanding of ubiquitylation in these processes is beginning to emerge, very little is known about the role deubiquitylation may play. Fat ... Facets in mouse (FAM) is substrate-specific deubiquitylating enzyme highly expressed in epithelia where it interacts with its substrate, beta-catenin. Here we show, in the polarized intestinal epithelial cell line T84, FAM localized to multiple points of protein trafficking. FAM interacted with beta-catenin and E-cadherin in T84 cells but only in subconfluent cultures. FAM extensively colocalized with beta-catenin in cytoplasmic puncta but not at sites of cell-cell contact as well as immunoprecipitating with beta-catenin and E-cadherin from a higher molecular weight complex ( approximately 500 kDa). At confluence FAM neither colocalized with, nor immunoprecipitated, beta-catenin or E-cadherin, which were predominantly in a larger molecular weight complex ( approximately 2 MDa) at the cell surface. Overexpression of FAM in MCF-7 epithelial cells resulted in increased beta-catenin levels, which localized to the plasma membrane. Expression of E-cadherin in L-cell fibroblasts resulted in the relocalization of FAM from the Golgi to cytoplasmic puncta. These data strongly suggest that FAM associates with E-cadherin and beta-catenin during trafficking to the plasma membrane.
Mesh Terms:
Actinin, Cadherins, Cell Adhesion, Cell Line, Cell Line, Tumor, Cell Membrane, Chromatography, Gel, Cytoplasm, Cytoskeletal Proteins, Detergents, Endopeptidases, Epithelium, Fibroblasts, Golgi Apparatus, Humans, Mass Spectrometry, Microscopy, Fluorescence, Myosins, Plasmids, Precipitin Tests, Protein Transport, Trans-Activators, Transfection, Ubiquitin, beta Catenin
Actinin, Cadherins, Cell Adhesion, Cell Line, Cell Line, Tumor, Cell Membrane, Chromatography, Gel, Cytoplasm, Cytoskeletal Proteins, Detergents, Endopeptidases, Epithelium, Fibroblasts, Golgi Apparatus, Humans, Mass Spectrometry, Microscopy, Fluorescence, Myosins, Plasmids, Precipitin Tests, Protein Transport, Trans-Activators, Transfection, Ubiquitin, beta Catenin
Mol. Biol. Cell
Date: Apr. 01, 2004
PubMed ID: 14742711
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