Polarity of TRH receptors in transfected MDCK cells is independent of endocytosis signals and G protein coupling. Academic Article uri icon

Overview

abstract

  • Information concerning the molecular sorting of G protein-coupled receptors in polarized epithelial cells is limited. Therefore, we have expressed the receptor for thyrotropin-releasing hormone (TRH) in Madin-Darby canine kidney (MDCK) cells by adenovirus-mediated gene transfer to determine its distribution in a model cell system and to begin analyzing the molecular information responsible for its distribution. Equilibrium binding of [methyl-3H]TRH to apical and basolateral surfaces of polarized MDCK cells reveals that TRH receptors are expressed predominantly (>80%) on the basolateral cell surface. Receptors undergo rapid endocytosis following agonist binding; up to 80% are internalized in 15 min. A mutant receptor missing the last 59 residues, C335Stop, is poorly internalized (<10%) but is nevertheless basolaterally expressed (>85%). A second mutant TRH receptor, delta218-263, lacks essentially all of the third intracellular loop and is not coupled to G proteins on binding agonist. This receptor internalizes TRH approximately half as efficiently as wild-type TRH receptors but is nevertheless strongly polarized to the basolateral surface (>90%). These results indicate that molecular sequences responsible for basolateral accumulation of TRH receptors can be segregated from signals for ligand-induced receptor endocytosis and coupling to heterotrimeric G proteins.

publication date

  • March 1, 1996

Research

keywords

  • Endocytosis
  • GTP-Binding Proteins
  • Receptors, Thyrotropin-Releasing Hormone
  • Signal Transduction

Identity

Scopus Document Identifier

  • 0029985684

Digital Object Identifier (DOI)

  • 10.1152/ajpcell.1996.270.3.C753

PubMed ID

  • 8638654

Additional Document Info

volume

  • 270

issue

  • 3 Pt 1