Involved in myo-inositol synthesis. D-glucose 6-phosphate = 1D-myo-inositol 3-phosphate kcat is 4.0 min(-1) for D-glucose 6-phosphate. kcat is 3.6 min(-1) for NAD(+). Polyol metabolism; myo-inositol biosynthesis; myo-inositol from D-glucose 6-phosphate: step 1/2. A number of isoforms are produced. According to EST sequences. Expressed in siliques, leaves, roots, seed endosperm, but not in embryos. Highest expression in seeds. In leaves, only expressed in hydathodes and vascular tissue. No spontaneous lesion formation and no significant alteration in the response to abscisic acid. Increased susceptibility to bacterial and fungal pathogens. Belongs to the myo-inositol 1-phosphate synthase family. Was called MIPS1 in PubMed:18603618.