Category: signaling
Membrane phosphatidylinositol cycle and downstream signaling. PI(4,5)P2 is cleaved by PLC (phospholipase C, Gq-coupled or RTK-coupled) into IP3 (releases ER Ca2+ via IP3R) and DAG (activates PKC). IP3 is degraded by sequential phosphatases — inositol monophosphatase (IMPA1) is the proposed LITHIUM TARGET for bipolar disorder ("inositol depletion hypothesis"). Lithium also inhibits GSK-3β; the relative contribution of each to mood-stabilization is debated. Inositol supplementation has been investigated for PCOS, depression, and lithium-augmentation strategies (with mixed evidence). PI(3,4,5)P3 (made from PI(4,5)P2 by PI3K) is a separate signaling axis driving AKT — see mtor_signaling pathway.