Molecular cloning, water channel activity and tissue specific expression of two isoforms of radish [Raphanus sativus] vacuolar aquaporin

• Published in: Plant and cell physiology Vol. 39; no. 9; pp. 905 - 913
• Main Authors: Higuchi, T. (Nagoya Univ. (Japan)), Suga, S, Tsuchiya, T, Hisada, H, Morishima, S, Okada, Y, Maeshima, M
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.09.1998
• Subjects: Absorption. Translocation of ions and substances. Permeability; Agronomy. Soil science and plant productions; Amino Acid Sequence; Animals; Aquaporins - chemistry; Aquaporins - genetics; Aquaporins - physiology; Arabidopsis - genetics; Biological and medical sciences; Cell Membrane Permeability; cell membranes; Cell physiology; CLONACION MOLECULAR; CLONAGE MOLECULAIRE; cloning; Cloning, Molecular; complementary DNA; cotyledons; Economic plant physiology; Female; Fundamental and applied biological sciences. Psychology; genbank/ab010416; genbank/d84669; gene expression; Gene Expression Regulation, Plant; genes; genetic regulation; hypocotyls; Intracellular Membranes - metabolism; MOLECULAR CLONING; Molecular Sequence Data; nucleotide sequences; Nutrition. Photosynthesis. Respiration. Metabolism; Oocytes - physiology; PERMEABILIDAD; PERMEABILITE; PERMEABILITY; Plant physiology and development; Plasma membrane and permeation; protein composition; Protein Isoforms - chemistry; Protein Isoforms - genetics; Protein Isoforms - physiology; Raphanus; RAPHANUS SATIVUS; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; roots; Sequence Alignment; Sequence Homology, Amino Acid; VACUOLA; VACUOLE; VACUOLES; Vacuoles - metabolism; Vegetables - genetics; Vegetables - metabolism; vm23 proteins; Water; water transfer; Xenopus laevis; Water; Tonoplast; Cell permeability; Isozyme; Biological transport; Tissue specificity; Gene expression; Vacuole; Raphanus sativus; Vegetable crop; Cruciferae; Dicotyledones; Angiospermae; Spermatophyta; Membrane channel; Molecular cloning; Aquaporin; Aminoacid sequence
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/oxfordjournals.pcp.a029453

A major membrane intrinsic protein (VM23) in vacuoles of radish (Raphanus) tap root was investigated. The cDNAs for two isoforms of VM23, gamma- and delta-VM23, encode polypeptides of 253 and 248 amino acids, respectively. gamma- and delta-VM23 correspond to the gamma and delta-TIP (tonoplast intrinsic protein) of Arabidopsis. The deduced amino acid sequences of the two VM23 isoforms were 60% identical. The amino-terminal sequence of gamma-VM23 showed agreement with the direct sequence of the purified VM23, suggesting that gamma-VM23 is the most abundant molecule among the VM23 isoforms. When mRNAs of gamma- and delta-VM23 were injected into Xenopus oocytes, the osmotic water permeability of oocytes increased 6-fold (60 to 200 mu-m s(-1) of the control oocytes. The transcripts of both isoforms were detected in a high level in growing hypocotyls and young leaves, but delta-VM23 was not detected in seedling roots. LIght illumination enhanced the transcription of two genes of VM23 in cotyledons and roots but suppressed their expression in hypocotyls the growth of which was inhibited by light. These findings suggest that the expression of VM23 is tightly related to cell elongation