Logo of plntcellLink to Publisher's site
Plant Cell. Apr 1996; 8(4): 587–599.
PMCID: PMC161122

Characterization of a new vacuolar membrane aquaporin sensitive to mercury at a unique site.


The membranes of plant and animal cells contain aquaporins, proteins that facilitate the transport of water. In plants, aquaporins are found in the vacuolar membrane (tonoplast) and the plasma membrane. Many aquaporins are mercury sensitive, and in AQP1, a mercury-sensitive cysteine residue (Cys-189) is present adjacent to a conserved Asn-Pro-Ala motif. Here, we report the molecular analysis of a new Arabidopsis aquaporin, delta-TIP (for tonoplast intrinsic protein), and show that it is located in the tonoplast. The water channel activity of delta-TIP is sensitive to mercury. However, the mercury-sensitive cysteine residue found in mammalian aquaporins is not present in delta-TIP, or in gamma-TIP, a previously characterized mercury-sensitive tonoplast aquaporin. Site-directed mutagenesis was used to identify the mercury-sensitive site in these two aquaporins as Cys-116 and Cys-118 for delta-TIP and gamma-TIP, respectively. These mutations are at a conserved position in a presumed membrane-spanning domain not previously known to have a role in aquaporin mercury sensitivity. Comparing the tissue expression patterns of delta-TIP with gamma-TIP and alpha-TIP showed that the TIPs are differentially expressed.

Full Text

The Full Text of this article is available as a PDF (2.4M).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Agre P, Brown D, Nielsen S. Aquaporin water channels: unanswered questions and unresolved controversies. Curr Opin Cell Biol. 1995 Aug;7(4):472–483. [PubMed]
  • Cao Y, Anderova M, Crawford NM, Schroeder JI. Expression of an outward-rectifying potassium channel from maize mRNA and complementary RNA in Xenopus oocytes. Plant Cell. 1992 Aug;4(8):961–969. [PMC free article] [PubMed]
  • Chrispeels MJ, Agre P. Aquaporins: water channel proteins of plant and animal cells. Trends Biochem Sci. 1994 Oct;19(10):421–425. [PubMed]
  • Chrispeels MJ, Maurel C. Aquaporins: the molecular basis of facilitated water movement through living plant cells? Plant Physiol. 1994 May;105(1):9–13. [PMC free article] [PubMed]
  • Daniels MJ, Mirkov TE, Chrispeels MJ. The plasma membrane of Arabidopsis thaliana contains a mercury-insensitive aquaporin that is a homolog of the tonoplast water channel protein TIP. Plant Physiol. 1994 Dec;106(4):1325–1333. [PMC free article] [PubMed]
  • Echevarria M, Windhager EE, Tate SS, Frindt G. Cloning and expression of AQP3, a water channel from the medullary collecting duct of rat kidney. Proc Natl Acad Sci U S A. 1994 Nov 8;91(23):10997–11001. [PMC free article] [PubMed]
  • Elledge SJ, Mulligan JT, Ramer SW, Spottswood M, Davis RW. Lambda YES: a multifunctional cDNA expression vector for the isolation of genes by complementation of yeast and Escherichia coli mutations. Proc Natl Acad Sci U S A. 1991 Mar 1;88(5):1731–1735. [PMC free article] [PubMed]
  • Farinas J, Van Hoek AN, Shi LB, Erickson C, Verkman AS. Nonpolar environment of tryptophans in erythrocyte water channel CHIP28 determined by fluorescence quenching. Biochemistry. 1993 Nov 9;32(44):11857–11864. [PubMed]
  • Höfte H, Hubbard L, Reizer J, Ludevid D, Herman EM, Chrispeels MJ. Vegetative and Seed-Specific Forms of Tonoplast Intrinsic Protein in the Vacuolar Membrane of Arabidopsis thaliana. Plant Physiol. 1992 Jun;99(2):561–570. [PMC free article] [PubMed]
  • Jung JS, Bhat RV, Preston GM, Guggino WB, Baraban JM, Agre P. Molecular characterization of an aquaporin cDNA from brain: candidate osmoreceptor and regulator of water balance. Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):13052–13056. [PMC free article] [PubMed]
  • Kaldenhoff R, Kölling A, Meyers J, Karmann U, Ruppel G, Richter G. The blue light-responsive AthH2 gene of Arabidopsis thaliana is primarily expressed in expanding as well as in differentiating cells and encodes a putative channel protein of the plasmalemma. Plant J. 1995 Jan;7(1):87–95. [PubMed]
  • Ma T, Frigeri A, Hasegawa H, Verkman AS. Cloning of a water channel homolog expressed in brain meningeal cells and kidney collecting duct that functions as a stilbene-sensitive glycerol transporter. J Biol Chem. 1994 Aug 26;269(34):21845–21849. [PubMed]
  • Macey RI. Transport of water and urea in red blood cells. Am J Physiol. 1984 Mar;246(3 Pt 1):C195–C203. [PubMed]
  • Maggio A, Joly RJ. Effects of Mercuric Chloride on the Hydraulic Conductivity of Tomato Root Systems (Evidence for a Channel-Mediated Water Pathway). Plant Physiol. 1995 Sep;109(1):331–335. [PMC free article] [PubMed]
  • Maurel C, Reizer J, Schroeder JI, Chrispeels MJ. The vacuolar membrane protein gamma-TIP creates water specific channels in Xenopus oocytes. EMBO J. 1993 Jun;12(6):2241–2247. [PMC free article] [PubMed]
  • Maurel C, Kado RT, Guern J, Chrispeels MJ. Phosphorylation regulates the water channel activity of the seed-specific aquaporin alpha-TIP. EMBO J. 1995 Jul 3;14(13):3028–3035. [PMC free article] [PubMed]
  • Mulders SM, Preston GM, Deen PM, Guggino WB, van Os CH, Agre P. Water channel properties of major intrinsic protein of lens. J Biol Chem. 1995 Apr 14;270(15):9010–9016. [PubMed]
  • Pao GM, Wu LF, Johnson KD, Höfte H, Chrispeels MJ, Sweet G, Sandal NN, Saier MH., Jr Evolution of the MIP family of integral membrane transport proteins. Mol Microbiol. 1991 Jan;5(1):33–37. [PubMed]
  • Pratz J, Ripoche P, Corman B. Evidence for proteic water pathways in the luminal membrane of kidney proximal tubule. Biochim Biophys Acta. 1986 Apr 14;856(2):259–266. [PubMed]
  • Preston GM, Carroll TP, Guggino WB, Agre P. Appearance of water channels in Xenopus oocytes expressing red cell CHIP28 protein. Science. 1992 Apr 17;256(5055):385–387. [PubMed]
  • Preston GM, Jung JS, Guggino WB, Agre P. The mercury-sensitive residue at cysteine 189 in the CHIP28 water channel. J Biol Chem. 1993 Jan 5;268(1):17–20. [PubMed]
  • Preston GM, Jung JS, Guggino WB, Agre P. Membrane topology of aquaporin CHIP. Analysis of functional epitope-scanning mutants by vectorial proteolysis. J Biol Chem. 1994 Jan 21;269(3):1668–1673. [PubMed]
  • Qi X, Tai CY, Wasserman BP. Plasma membrane intrinsic proteins of Beta vulgaris L. Plant Physiol. 1995 May;108(1):387–392. [PMC free article] [PubMed]
  • Reizer J, Reizer A, Saier MH., Jr The MIP family of integral membrane channel proteins: sequence comparisons, evolutionary relationships, reconstructed pathway of evolution, and proposed functional differentiation of the two repeated halves of the proteins. Crit Rev Biochem Mol Biol. 1993;28(3):235–257. [PubMed]
  • Sarafian V, Kim Y, Poole RJ, Rea PA. Molecular cloning and sequence of cDNA encoding the pyrophosphate-energized vacuolar membrane proton pump of Arabidopsis thaliana. Proc Natl Acad Sci U S A. 1992 Mar 1;89(5):1775–1779. [PMC free article] [PubMed]
  • Smith BL, Agre P. Erythrocyte Mr 28,000 transmembrane protein exists as a multisubunit oligomer similar to channel proteins. J Biol Chem. 1991 Apr 5;266(10):6407–6415. [PubMed]
  • Tsang SS, Yin X, Guzzo-Arkuran C, Jones VS, Davison AJ. Loss of resolution in gel electrophoresis of RNA: a problem associated with the presence of formaldehyde gradients. Biotechniques. 1993 Mar;14(3):380–381. [PubMed]
  • Unfried I, Stocker U, Gruendler P. Nucleotide sequence of the 18S rRNA gene from Arabidopsis thaliana Co10. Nucleic Acids Res. 1989 Sep 25;17(18):7513–7513. [PMC free article] [PubMed]
  • van der Meer IM, Stam ME, van Tunen AJ, Mol JN, Stuitje AR. Antisense inhibition of flavonoid biosynthesis in petunia anthers results in male sterility. Plant Cell. 1992 Mar;4(3):253–262. [PMC free article] [PubMed]
  • Van Hoek AN, Luthjens LH, Hom ML, Van Os CH, Dempster JA. A 30 kDa functional size for the erythrocyte water channel determined in situ by radiation inactivation. Biochem Biophys Res Commun. 1992 May 15;184(3):1331–1338. [PubMed]
  • Van Hoek AN, Wiener M, Bicknese S, Miercke L, Biwersi J, Verkman AS. Secondary structure analysis of purified functional CHIP28 water channels by CD and FTIR spectroscopy. Biochemistry. 1993 Nov 9;32(44):11847–11856. [PubMed]
  • Verbavatz JM, Brown D, Sabolić I, Valenti G, Ausiello DA, Van Hoek AN, Ma T, Verkman AS. Tetrameric assembly of CHIP28 water channels in liposomes and cell membranes: a freeze-fracture study. J Cell Biol. 1993 Nov;123(3):605–618. [PMC free article] [PubMed]
  • Wayne R, Tazawa M. Nature of the water channels in the internodal cells of Nitellopsis. J Membr Biol. 1990 Jun;116(1):31–39. [PubMed]
  • Zeidel ML, Nielsen S, Smith BL, Ambudkar SV, Maunsbach AB, Agre P. Ultrastructure, pharmacologic inhibition, and transport selectivity of aquaporin channel-forming integral protein in proteoliposomes. Biochemistry. 1994 Feb 15;33(6):1606–1615. [PubMed]
  • Zhang RB, Verkman AS. Water and urea permeability properties of Xenopus oocytes: expression of mRNA from toad urinary bladder. Am J Physiol. 1991 Jan;260(1 Pt 1):C26–C34. [PubMed]
  • Zhang R, van Hoek AN, Biwersi J, Verkman AS. A point mutation at cysteine 189 blocks the water permeability of rat kidney water channel CHIP28k. Biochemistry. 1993 Mar 30;32(12):2938–2941. [PubMed]

Articles from The Plant Cell are provided here courtesy of American Society of Plant Biologists


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


  • Compound
    PubChem Compound links
  • Gene
    Gene links
  • Gene (nucleotide)
    Gene (nucleotide)
    Records in Gene identified from shared sequence links
  • GEO Profiles
    GEO Profiles
    Related GEO records
  • HomoloGene
    HomoloGene links
  • MedGen
    Related information in MedGen
  • Nucleotide
    Published Nucleotide sequences
  • Pathways + GO
    Pathways + GO
    Pathways, annotations and biological systems (BioSystems) that cite the current article.
  • Protein
    Published protein sequences
  • PubMed
    PubMed citations for these articles
  • Substance
    PubChem Substance links

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...