title: Recycling of galectin-3 in epithelial cells.
abstract: Galectins, a family of β-galactoside binding proteins, do not possess a signalling sequence to enter the endoplasmic reticulum as a starting point for the classical secretory pathway. They use a so-called unconventional secretion mechanism for translocation across the plasma membrane and/or into the lumen of transport vesicles. The β-galactoside binding protein galectin-3 is highly expressed in a variety of epithelial cell lines. Polarized MDCK cells secrete this lectin predominantly into the apical medium. The lectin re-enters the cell by non-clathrin mediated endocytosis and passages through endosomal organelles. This internalized galectin-3 plays an important role in apical protein trafficking by directing the subcellular targeting of apical glycoproteins via oligomerization into high molecular weight clusters, a process that can be fine-tuned by changes in the environmental pH. Following release at the apical plasma membrane, the lectin can reenter the cell for another round of recycling and apical protein sorting. This review will briefly address galectin-3-functions in epithelia and focus on distinct phases in apical recycling of the lectin.
authors.affiliation: Department of Cell Biology and Cell Pathology, Philipps University of Marburg, Marburg, Germany.
authors.forename: Ellena
authors.initials: E
authors.lastname: Hönig
authors.affiliation: Department of Cell Biology and Cell Pathology, Philipps University of Marburg, Marburg, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Schneider
authors.affiliation: Department of Cell Biology and Cell Pathology, Philipps University of Marburg, Marburg, Germany. Electronic address: jacob@staff.uni-marburg.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Jacob
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D016764:Cell Polarity / Q000502:physiology; D004285:Dogs; D004705:Endocytosis / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D037502:Galectin 3 / Q000378:metabolism*; D061985:Madin Darby Canine Kidney Cells; D021381:Protein Transport / Q000502:physiology*; D022161:Transport Vesicles / Q000378:metabolism
chemical_list: D037502:Galectin 3
keywords: Apical targeting; Endosome; Galectin; Polarized sorting; Rab; SNAP-tag