Histochemistry and Cell Biology

, Volume 104, Issue 1, pp 1–9

Cellular distribution of the aquaporins: A family of water channel proteins

  • Dennis Brown
  • Toshiya Katsura
  • Megumi Kawashima
  • A. S. Verkman
  • Ivan Sabolic
Review

DOI: 10.1007/BF01464780

Cite this article as:
Brown, D., Katsura, T., Kawashima, M. et al. Histochem Cell Biol (1995) 104: 1. doi:10.1007/BF01464780

Abstract

A group of transmembrane proteins that are related to the major intrinsic protein of lens fibers (MIP26) have been named “aquaporins” to reflect their role as water channels. These proteins are located at strategic membrane sites in a variety of epithelia, most of which have well-defined physiological functions in fluid absorption or secretion. However, some aquaporins have been localized in cell types where their role is at present unknown. Most of the aquaporins are delivered to the plasma membrane in a non-regulated (constitutive) fashion, but AQP2 enters the regulated exocytotic pathway and its membrane expression is controlled by the action of the antidiuretic hormone, vasopressin. These pathways of constitutive versus regulated delivery to the plasma membrane have been reconstituted in transfected LLC-PK1 epithelial cells, indicating that the information encoded within the protein sequence is sufficient to allow sorting of newly synthesized protein into distinct intracellular vesicles. Finally, different members of the aquaporin family can be targeted to apical, basolateral or both apical and basolateral plasma membrane domains of polarized epithelial cells. This implies that signals for the polarized targeting of these proteins also is located in non-homologous regions of these similar proteins. Thus, future investigations on the aquaporin family of proteins will provide important information not only on the physiology of membrane transport processes in many cell types, but also on the targeting and trafficking signals that allow proteins to enter distinct intracellular vesicular pathways in epithelial cells. In the case of AQP2, the availability of the transfected cell culture system will allow the intracellular signaling pathway, and the accessory molecules that are involved in this pathway, to be dissected and identified.

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • Dennis Brown
    • 1
    • 2
  • Toshiya Katsura
    • 1
    • 2
  • Megumi Kawashima
    • 1
    • 2
  • A. S. Verkman
    • 3
  • Ivan Sabolic
    • 1
    • 2
  1. 1.Renal Unit, Massachusetts General HospitalBostonUSA
  2. 2.Department of PathologyHarvard Medical SchoolBostonUSA
  3. 3.Departments of Medicine and Physiology, Cardiovascular Research InstituteUniversity of CaliforniaSan FranciscoUSA
  4. 4.Massachusetts General Hospital EastCharlestownUSA
  5. 5.Institute for Medical Research and Occupational HealthUniversity of ZagrebZagrebCroatia