Majumder A L, Johnson M D, Henry S A
Department of Botany, Bose Institute, Calcutta, India.
Biochim Biophys Acta. 1997 Sep 4;1348(1-2):245-56. doi: 10.1016/s0005-2760(97)00122-7.
1L-myo-Inositol-1-phosphate synthase catalyzes the conversion of D-glucose 6-phosphate to 1L-myo-inositol-1-phosphate, the first committed step in the production of all inositol-containing compounds, including phospholipids, either directly or by salvage. The enzyme exists in a cytoplasmic form in a wide range of plants, animals, and fungi. It has also been detected in several bacteria and a chloroplast form is observed in alga and higher plants. The enzyme has been purified from a wide range of organisms and its active form is a multimer of identical subunits ranging in molecular weight from 58,000 to 67,000. The activity of the synthase is stimulated by NH4Cl and inhibited by glucitol 6-phosphate and 2-deoxyglucose 6-phosphate. Structural genes (INO1) encoding the 1L-myo-inositol-1-phosphate synthase subunit have been isolated from several eukaryotic microorganisms and higher plants. In baker's yeast, Saccharomyces cerevisiae, the transcriptional regulation of the INO1 gene has been studied in detail and its expression is sensitive to the availability of phospholipid precursors as well as growth phase. The regulation of the structural gene encoding 1L-myo-inositol-1-phosphate synthase has also been analyzed at the transcriptional level in the aquatic angiosperm, Spirodela polyrrhiza and the halophyte, Mesembryanthemum crystallinum.
1L-肌醇-1-磷酸合酶催化6-磷酸-D-葡萄糖转化为1L-肌醇-1-磷酸，这是包括磷脂在内的所有含肌醇化合物合成过程中的第一个关键步骤，这些化合物可直接合成或通过补救途径合成。该酶以细胞质形式存在于多种植物、动物和真菌中。在几种细菌中也检测到了该酶，并且在藻类和高等植物中观察到了叶绿体形式。该酶已从多种生物体中纯化出来，其活性形式是由分子量在58,000至67,000之间的相同亚基组成的多聚体。合酶的活性受到氯化铵的刺激，并受到6-磷酸葡糖醇和6-磷酸-2-脱氧葡萄糖的抑制。编码1L-肌醇-1-磷酸合酶亚基的结构基因（INO1）已从几种真核微生物和高等植物中分离出来。在面包酵母酿酒酵母中，已对INO1基因的转录调控进行了详细研究，其表达对磷脂前体的可用性以及生长阶段敏感。在水生被子植物多根紫萍和盐生植物晶状拟南芥中，也在转录水平上分析了编码1L-肌醇-1-磷酸合酶的结构基因的调控。
