Additional Inositol Lipid Compounds

In response to GPCR and receptor tyrosine kinase activation, PI 3-kinase phosphorylates some inositol lipids, such as PI(3,4,5)P₃, and PLC mediates inositol lipid cleavage to generate further second messengers such as DAG and IP₃. IP₃ subsequently acts upon IP₃ receptors located in the ER membrane and mediates Ca²⁺ release.

Regulation of inositol lipid signaling pathways is through phosphorylation (e.g. by inositol-tetrakisphosphate 1-kinase) and dephosphorylation (e.g. by inositol monophosphatase (IMPase)) of inositol lipids. This large group of proteins constitute a major intracellular signal transduction network. Because of this, inositol lipids are involved in a vast number of physiological processes.