Selectivity of the renal collecting duct water channel aquaporin-3. Academic Article uri icon

Overview

abstract

  • Aquaporin-3 (AQP3) is a water channel found in the basolateral cell membrane of principal cells of the renal collecting tubule as well as in other epithelia. To examine the selectivity of AQP3, the permeability to water (Pf), urea (Pur), and glycerol (Pgly) of Xenopus oocytes injected with cRNA encoding AQP3 was measured. Oocytes injected with cRNA encoding either human or rat aquaporin-1 (AQP1) were used as controls. Although both aquaporins permit water flow across the cell membrane, only AQP3 was permeable to glycerol and urea (Pgly > Pur). The uptake of glycerol into oocytes expressing AQP3 was linear up to 165 mM. For AQP3 the Arrhenius energy of activation for Pf was 3 kcal/mol, whereas for Pgly and Pur it was >12 kcal/mol. The sulfhydryl reagent p-chloromercuriphenylsulfonate (1 mM) abolished Pf of AQP3, whereas it did not affect Pgly. In addition, phloretin (0.1 mM) inhibited Pf of AQP3 by 35%, whereas it did not alter Pgly or Pur. We conclude that water does not share the same pathway with glycerol or urea in AQP3 and that this aquaporin, therefore, forms a water-selective channel.

publication date

  • October 11, 1996

Research

keywords

  • Aquaporins
  • Cell Membrane Permeability
  • Escherichia coli Proteins
  • Ion Channels
  • Kidney Tubules, Collecting

Identity

Scopus Document Identifier

  • 0029834336

Digital Object Identifier (DOI)

  • 10.1074/jbc.271.41.25079

PubMed ID

  • 8810261

Additional Document Info

volume

  • 271

issue

  • 41