title: Differentially expressed forms of 1-L-myo-inositol-1-phosphate synthase (EC 5.5.1.4) in Phaseolus vulgaris.
abstract: We have characterized two distinct polypeptides with 1-L-myo-inositol-1-phosphate synthase (MI-1-P synthase) activity that are differentially expressed during development in Phaseolus vulgaris. Western analyses, enzyme assays, and partial purification of MI-1-P synthase during embryonic and postembryonic development show that its expression is temporally and spatially regulated. Developmental Western analyses of soluble proteins detect a small protein, approximately 33 kDa, with MI-1-P synthase activity during the globular stage (stage II) of embryogenesis and in mature roots. Expression of this small protein is also enriched in thylakoidal membranes of fractionated leaf chloroplasts, although Western analyses of total soluble leaf proteins show no cross-reacting material. In contrast, a larger protein, approximately 56 kDa, with MI-1-P synthase activity is present during the cotyledonary phase (stage IV) of embryogenesis in green cotyledons of seedlings and in young roots.
authors.affiliation: Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama 35487, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Johnson
authors.forename: X
authors.initials: X
authors.lastname: Wang
mesh_terms: D015153:Blotting, Western; D002736:Chloroplasts / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D018548:Cotyledon; D004591:Electrophoresis, Polyacrylamide Gel; D007887:Fabaceae / Q000201:enzymology* / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D008970:Molecular Weight; D007296:Myo-Inositol-1-Phosphate Synthase / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D015388:Organelles / Q000201:enzymology; D018515:Plant Leaves; D018517:Plant Roots; D010946:Plants, Medicinal
chemical_list: D007527:Isoenzymes; D007296:Myo-Inositol-1-Phosphate Synthase