描述
Inositol (also known as myo-inositol) is a carbocyclic polyol that plays an important role as the structural basis for a number of secondary messengers in eukaryotic cells, including inositol phosphates, phosphatidylinositol (PI) and phosphatidylinositol phosphate (PIP) lipids. It is found in many foods, in particular, in cereals with high bran content, nuts, beans, and fruit, especially cantaloupe melons and oranges. Inositol is not considered a vitamin itself because it can be synthesised by the body. Myo-Inositol is synthesized from glucose-6-phosphate (G-6-P) in two steps. First, G-6-P is isomerised by inositol-3-phosphate synthase (ASYNA1) to myo-inositol 3-phosphate, which is then dephosphorylated by inositol monophosphatase (IMPase 1) to give free myo-inositol. The synthesis of phosphatidylinositol is catalyzed by phosphatidylinositol synthase and involves CDP-diacylglycerol and myo-inositol. Phosphatidylinositol phosphate lipids are a product of class I, II and III phosphoinositide 3-kinases (PI 3-kinases) acting on phosphatidylinositol. Many inositol phosphates are made by the hydrolysis of phosphatidylinositol phosphates by phospholipase C. They may also be synthesized or remodeled via various kinases and phosphatases.