title: Localization of myo-inositol-1-phosphate synthase to the endosperm in developing seeds of Arabidopsis.
abstract: Expression and localization of myo-inositol-1-phosphate synthase (MIPS) in developing seeds of Arabidopsis thaliana was investigated. MIPS is an essential enzyme for production of inositol and inositol phosphates via its circularization of glucose-6-phosphate as the initial step. myo-inositol-6-phosphate (InsP(6) or phytic acid) is the predominant form of phosphorus found in seeds and accumulates as a consequence of MIPS action. Three MIPS genes have been identified in Arabidopsis, all of which were expressed not only in siliques but in both leaves and roots. Immunoelectron microscopy using a MIPS antibody showed that MIPS localizes to the cytosol primarily in the endosperm during seed development and not in the embryo. This is consistent with results obtained using fluorescent microscopy and western blot analysis that showed a similar pattern of localization. However, InsP(6), which is the final product of inositol phosphate metabolism, was present mainly in the embryo. This suggests that a complex interaction between the endosperm and embryo occurs during the synthesis and subsequent accumulation of InsP(6) in developing seeds of Arabidopsis.
authors.affiliation: Department of Biology, Graduate School of Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, 657-8501 Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Mitsuhashi
authors.forename: Maki
authors.initials: M
authors.lastname: Kondo
authors.forename: Satoru
authors.initials: S
authors.lastname: Nakaune
authors.forename: Miwa
authors.initials: M
authors.lastname: Ohnishi
authors.forename: Makoto
authors.initials: M
authors.lastname: Hayashi
authors.forename: Ikuko
authors.initials: I
authors.lastname: Hara-Nishimura
authors.forename: Alan
authors.initials: A
authors.lastname: Richardson
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Fukaki
authors.forename: Mikio
authors.initials: M
authors.lastname: Nishimura
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Mimura
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000201:enzymology* / Q000235:genetics; D003600:Cytosol / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007296:Myo-Inositol-1-Phosphate Synthase / Q000235:genetics / Q000378:metabolism*; D010833:Phytic Acid / Q000096:biosynthesis*; D012639:Seeds / Q000196:embryology / Q000201:enzymology*
chemical_list: D010833:Phytic Acid; D007296:Myo-Inositol-1-Phosphate Synthase