Water Channels: Aquaporins

Mark J Daniels, The Scripps Research Institute, La Jolla, California, USA
Maarten J Chrispeels, University of California, San Diego, California, USA

Published online: April 2001

DOI: 10.1038/npg.els.0001289

Aquaporins are members of an ancient family of intrinsic membrane proteins that form pores or channels for water, and so facilitate the flow of water through cellular membranes in the presence of osmotic or hydrostatic gradients.

Keywords: membrane channel; membrane pore; MIP family; vasopressin

Figure 1. Cross-section of the AQP-1 tetramer crystallized in a lipid membrane and resolved by cryoelectron microscopy and image analysis. Electron density to 7 Å resolution is shown. One monomer is outlined and the six helices are indicated by asterisks. Scale bar indicates 10 Å. Electron density map courtesy of A. Cheng and A. K. Mitra.
Figure 2. Expression of a vacuolar membrane (tonoplast) aquaporin in 3–4-day-old maize roots. The intensity of the purple colour reflects the abundance of AQP mRNA in the cell. The mRNA is most abundant in the living cells of the root vascular cylinder, especially those of the phloem and those surrounding the xylem vessels. This cross section was taken 10 cm from the root tip. Image courtesy of F. Barrieu and M. J. Chrispeels.
close
 References
    Cheng A, van Hoek AN, Yeager M, Verkman AS and Mitra AK (1997) Three-dimensional organization of a human water channel. Nature 387: 627–630.
    Johansson I, Karlsson M, Shukla VK, Chrispeels MJ, Larsson C and Kjellbom P (1998) Water transport activity of the plasma membrane aquaporin PM28A is regulated by phosphorylation. The Plant Cell 10: 451–460.
    Maurel C, Reizer J, Schroeder JI and Chrispeels MJ (1993) The vacuolar membrane protein gamma-TIP creates water specific channels in Xenopus oocytes. EMBO Journal 12: 2241–2247.
    Preston GM, Carroll TP, Guggino WB and Agre P (1992) Appearance of water channels in Xenopus oocytes expressing red cell CHIP28 protein. Science 256: 385–387.
 Further Reading
    book Chepelinsky AB (1994) "The MIP transmembrane channel gene family". In: Peracchia C (ed.) Handbook of Membrane Channels. San Diego: Academic Press.
    Chrispeels MJ and Agre P (1994) Aquaporins: water channel proteins of plant and animal cells. Trends in Biological Sciences 19: 421–425.
    Knepper MA (1997) Molecular physiology of urinary concentrating mechanism: regulation of aquaporin water channels by vasopressin. American Journal of Physiology 272: F3–F12.
    Lee DM, King LS and Agre P (1997) The aquaporin family of water channel proteins in clinical medicine. Medicine 76: 141–156.
    Macey RI (1984) Transport of water and urea in red blood cells. American Journal of Physiology 246: C195–C203.
    Steudle E (1997) Water transport across plant tissue: Role of water channels. Biology of the Cell 89: 259–273.
    Verkman AS, van Hoek AN, Ma T et al. (1996) Water transport across mammalian cell membranes. American Journal of Physiology 270: C12–C30.

Related Sub-Topics:

Cell Membranes | Cellular Transport | Membrane Proteins | Roots and Root Systems
Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

Article Title: Water Channels: Aquaporins
 
How to Cite close
Daniels, Mark J, and Chrispeels, Maarten J(Apr 2001) Water Channels: Aquaporins. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001289]