title: Membrane receptor location defines receptor interaction with signaling proteins in a polarized epithelium.
abstract: Signal transduction from receptors is mediated by the interaction of activated receptors with proximate downstream signaling proteins. In polarized epithelial cells, the membrane is divided into subdomains: the apical and basolateral membranes. Membrane receptors may be present in one or both subdomains. Using a combination of immunoprecipitation and Western blot analyses, we tested the hypothesis that a tyrosine kinase growth factor receptor, epidermal growth factor receptor (EGFR), interacts with distinct signaling proteins when present at the apical vs. basolateral membrane of a polarized renal epithelial cell. We report here that tyrosine phosphorylation of phospholipase C-gamma (PLC-gamma) was induced only when basolateral EGFR was activated. In contrast, tyrosine phosphorylation of several other signaling proteins was increased by activation of receptor at either surface. All signaling proteins were distributed diffusely throughout the cytoplasm; however, PLC-gamma protein also displayed a concentration at lateral cell borders. These results demonstrate that in polarized epithelial cells the array of signaling pathways initiated by activation of a membrane receptor is defined, at least in part, by the membrane location of the receptor.
authors.affiliation: Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635, USA.
authors.forename: K
authors.initials: K
authors.lastname: Amsler
authors.forename: S K
authors.initials: SK
authors.lastname: Kuwada
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology*; D003902:Detergents / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D066246:ErbB Receptors / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D018374:LLC-PK1 Cells; D008565:Membrane Proteins / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000096:biosynthesis / Q000737:chemistry; D015398:Signal Transduction / Q000502:physiology*; D012995:Solubility; D013552:Swine; D014018:Tissue Distribution; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
chemical_list: D003902:Detergents; D007527:Isoenzymes; D008565:Membrane Proteins; D010750:Phosphoproteins; D014443:Tyrosine; D017830:Octoxynol; D066246:ErbB Receptors; D010738:Type C Phospholipases; D051966:Phospholipase C gamma