inositol1phosphate

Inositol-1-phosphate, commonly abbreviated IP1, is the monophosphorylated form of the cyclitol myo-inositol. It is an intermediate in the biosynthesis of inositol-containing lipids and phosphorylated inositol compounds, including phosphatidylinositol and inositol phosphates.

Biosynthesis and metabolism: In animals, plants, and fungi, IP1 is formed from glucose-6-phosphate by the enzyme myo-inositol-1-phosphate synthase (MIPS), yielding myo-inositol-1-phosphate. This compound is subsequently dephosphorylated by inositol monophosphatase to produce free myo-inositol, which serves as a precursor for phosphatidylinositol and various inositol phosphates. IP1 can also be interconverted by kinases and phosphatases within the broader inositol phosphate signaling network, giving rise to IP2, IP3, and higher phosphorylated species, with IP3 (inositol-1,4,5-trisphosphate) acting as a key second messenger.

Physiological role and significance: IP1 itself is primarily an intermediate metabolite, but its levels reflect activity of the inositol phosphate pathway. In humans, inositol monophosphatase is inhibited by lithium, which influences the recycling of free myo-inositol and downstream signaling. IP1 measurements are used as a surrogate readout for signaling activity in pharmacological studies and diagnostic assays.

Occurrence and applications: IP1 is found in organisms that synthesize inositol-containing lipids, including many bacteria and eukaryotes. It is a component of the pathway leading to phosphatidylinositol, a key lipid in cell membranes, and to various inositol phosphates that participate in cellular signaling and metabolism.