Ip1

Ip1, commonly written IP1, refers to inositol-1-phosphate, also known as myo-inositol monophosphate. It is a monoester of the cyclohexane sugar myo-inositol and a single phosphate group, and it belongs to the family of inositol phosphates involved in cellular metabolism and signaling.

Biosynthesis and metabolism: Inositol phosphates arise from inositol lipids in the cell. Phospholipase C hydrolyzes phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) to generate diacylglycerol and inositol trisphosphate (IP3). IP3 can be progressively dephosphorylated by inositol polyphosphate phosphatases to form IP2 and then IP1, which can be further dephosphorylated to free inositol. IP1 can also participate in recycling pathways that replenish cellular inositol pools.

Biological significance and measurement: IP1 itself has relatively modest signaling activity but serves as an intermediate in inositol phosphate metabolism and as a reservoir for recycled inositol. In research, IP1 accumulation is used as an indirect readout of Gq-coupled receptor activity because IP1 levels reflect sustained phospholipase C pathway engagement. Commercial assays measure IP1 using competitive immunoassays or fluorescence-based readouts, enabling high-throughput screening of receptor ligands and analysis of GPCR signaling dynamics.

See also: IP2, IP3, IP4 and broader inositol phosphate metabolism.