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Gene Review

PIP1A  -  aquaporin PIP1-1

Arabidopsis thaliana

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Disease relevance of PIP1A

  • The identification as a riboflavin-binding protein was confirmed by binding tests with an extract of Escherichia coli cells expressing the tobacco NtAQP1 as well as leaves of transgenic tobacco plants that overexpress NtAQP1 or were inhibited in PIP1 expression by antisense constructs [1].

High impact information on PIP1A

  • Matrix-assisted laser desorption/ionization time-of-flight analyses suggested that Plasma Membrane Intrinsic Protein2;2 (PIP2;2) is one of the abundantly expressed aquaporin isoforms in Arabidopsis root plasma membranes [2].
  • To address this issue, we constitutively overexpressed the Arabidopsis plasma membrane aquaporin, PIP1b, in transgenic tobacco plants [3].
  • 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 [4].
  • The appearance of intracellular structures containing PIP1 and PIP2 homologs was occasionally observed after 2 h of salt treatment [5].
  • The use of antipeptide antibodies that cross-reacted with isoforms of specific aquaporin subclasses revealed that the abundance of PIP1s decreased by 40% as early as 30 min after salt exposure, whereas PIP2 and TIP1 homologs showed a 20% to 40% decrease in abundance after 6 h of treatment [5].

Biological context of PIP1A


Anatomical context of PIP1A

  • A proteomic study reveals novel insights into the diversity of aquaporin forms expressed in the plasma membrane of plant roots [6].
  • Aquaporin belongs to a highly conserved group of membrane proteins called major intrinsic proteins that facilitate water transport across biological membranes [10].
  • ZmPIP1a and ZmPIP1b have no activity, and a review of the literature shows that most PIP1 proteins identified in other plants have no or very low activity in oocytes [11].
  • Compared with controls, the double antisense (dAS) plants had reduced amounts of PIP1 and PIP2 aquaporins, and the osmotic hydraulic conductivity of isolated root and leaf protoplasts was reduced 5- to 30-fold [12].
  • With flavin mononucleotide-agarose affinity columns, riboflavin-binding activity from microsomes of Cucurbita pepoL. hypocotyls was purified and identified as a specific PIP1-homologous protein of the aquaporin family [1].

Associations of PIP1A with chemical compounds

  • The responsiveness of each aquaporin to ABA were different, implying that the regulation of aquaporin expression involves both ABA-dependent and ABA-independent signaling pathways [10].
  • Thus the initiating methionine was acetylated or cleaved in native PIP1 and PIP2 isoforms respectively [13].
  • Computational methods were used to construct structural models of the putative pore regions of various plant MIPs based on homology modeling with the atomic resolution crystal structures of mammalian aquaporin 1 and the bacterial glycerol permease GlpF [14].

Other interactions of PIP1A

  • Together, our data provide evidence for the contribution of a single aquaporin gene to root water uptake and identify PIP2;2 as an aquaporin specialized in osmotic fluid transport [2].
  • Expression of RD28 caused a 10- to 15-fold increase in the osmotic water permeability of the oocytes, indicating that the protein creates water channels in the plasma membrane of the oocytes and is an aquaporin just like its homology gamma-TIP [15].
  • This led to the identification of a limited number of proteins: four different oleosins, ATS1, a protein homologous to calcium binding protein, a 11-beta-hydroxysteroid dehydrogenase-like protein, a probable aquaporin and a glycosylphosphatidylinositol-anchored protein with no known function [16].
  • When we expressed phaseolin, the major storage protein of common bean, or an epitope-tagged version of alpha-tonoplast intrinsic protein (alpha-TIP, a tonoplast aquaporin of PSV), in protoplasts derived from leaf tissues, these proteins were targeted to a compartment ranging in size from 2 to 5 microm in all three plant species [17].
  • In the present study, we investigated in young and mature leaves of Brassica napus L. the expression and localization of a vacuolar aquaporin homologous to radish gamma-tonoplast intrinsic protein/vacuolar-membrane integral protein of 23 kDa (TIP/VM 23) [18].

Analytical, diagnostic and therapeutic context of PIP1A

  • In the present work we combine separations of membrane proteins (by one- and two-dimensional gel electrophoresis) with identification by MS (matrix-assisted laser-desorption ionization-time-of-flight and electrospray-ionization tandem MS) to take an inventory of aquaporin isoforms expressed in the PM of Arabidopsis thaliana roots [6].


  1. A major integral protein of the plant plasma membrane binds flavin. Lorenz, A., Kaldenhoff, R., Hertel, R. Protoplasma (2003) [Pubmed]
  2. Role of a single aquaporin isoform in root water uptake. Javot, H., Lauvergeat, V., Santoni, V., Martin-Laurent, F., Güçlü, J., Vinh, J., Heyes, J., Franck, K.I., Schäffner, A.R., Bouchez, D., Maurel, C. Plant Cell (2003) [Pubmed]
  3. Overexpression of a plasma membrane aquaporin in transgenic tobacco improves plant vigor under favorable growth conditions but not under drought or salt stress. Aharon, R., Shahak, Y., Wininger, S., Bendov, R., Kapulnik, Y., Galili, G. Plant Cell (2003) [Pubmed]
  4. Characterization of a new vacuolar membrane aquaporin sensitive to mercury at a unique site. Daniels, M.J., Chaumont, F., Mirkov, T.E., Chrispeels, M.J. Plant Cell (1996) [Pubmed]
  5. Early effects of salinity on water transport in Arabidopsis roots. Molecular and cellular features of aquaporin expression. Boursiac, Y., Chen, S., Luu, D.T., Sorieul, M., van den Dries, N., Maurel, C. Plant Physiol. (2005) [Pubmed]
  6. A proteomic study reveals novel insights into the diversity of aquaporin forms expressed in the plasma membrane of plant roots. Santoni, V., Vinh, J., Pflieger, D., Sommerer, N., Maurel, C. Biochem. J. (2003) [Pubmed]
  7. From genome to function: the Arabidopsis aquaporins. Quigley, F., Rosenberg, J.M., Shachar-Hill, Y., Bohnert, H.J. Genome Biol. (2002) [Pubmed]
  8. Eight cDNA encoding putative aquaporins in Vitis hybrid Richter-110 and their differential expression. Baiges, I., Schäffner, A.R., Mas, A. J. Exp. Bot. (2001) [Pubmed]
  9. Regulation of the Arabidopsis thaliana aquaporin gene AthH2 (PIP1b). Kaldenhoff, R., Kölling, A., Richter, G. J. Photochem. Photobiol. B, Biol. (1996) [Pubmed]
  10. An expression analysis of a gene family encoding plasma membrane aquaporins in response to abiotic stresses in Arabidopsis thaliana. Jang, J.Y., Kim, D.G., Kim, Y.O., Kim, J.S., Kang, H. Plant Mol. Biol. (2004) [Pubmed]
  11. Plasma membrane intrinsic proteins from maize cluster in two sequence subgroups with differential aquaporin activity. Chaumont, F., Barrieu, F., Jung, R., Chrispeels, M.J. Plant Physiol. (2000) [Pubmed]
  12. Plasma membrane aquaporins play a significant role during recovery from water deficit. Martre, P., Morillon, R., Barrieu, F., North, G.B., Nobel, P.S., Chrispeels, M.J. Plant Physiol. (2002) [Pubmed]
  13. Methylation of aquaporins in plant plasma membrane. Santoni, V., Verdoucq, L., Sommerer, N., Vinh, J., Pflieger, D., Maurel, C. Biochem. J. (2006) [Pubmed]
  14. Homology modeling of representative subfamilies of Arabidopsis major intrinsic proteins. Classification based on the aromatic/arginine selectivity filter. Wallace, I.S., Roberts, D.M. Plant Physiol. (2004) [Pubmed]
  15. The plasma membrane of Arabidopsis thaliana contains a mercury-insensitive aquaporin that is a homolog of the tonoplast water channel protein TIP. Daniels, M.J., Mirkov, T.E., Chrispeels, M.J. Plant Physiol. (1994) [Pubmed]
  16. Protein composition of oil bodies in Arabidopsis thaliana ecotype WS. Jolivet, P., Roux, E., D'Andrea, S., Davanture, M., Negroni, L., Zivy, M., Chardot, T. Plant Physiol. Biochem. (2004) [Pubmed]
  17. Identification of the protein storage vacuole and protein targeting to the vacuole in leaf cells of three plant species. Park, M., Kim, S.J., Vitale, A., Hwang, I. Plant Physiol. (2004) [Pubmed]
  18. Expression and distribution of a vaculoar aquaporin in young and mature leaf tissues of Brassica napus in relation to water fluxes. Frangne, N., Maeshima, M., Schäffner, A.R., Mandel, T., Martinoia, E., Bonnemain, J.L. Planta (2001) [Pubmed]
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