Practice question

Signal transduction from surface receptors cytosol heavily relies phosphatidylinositol derivatives rather than bulk phosphatidylcholine ganglioside cholesterol structural lipids which play scaffolding roles. Plasma membrane PI phosphorylated PI4K to PI four phosphate then PIP5K to PI four five bisphosphate comprising one percent phospholipid yet pivotal recruitment PH domain proteins Dok. Ligand binding Gq coupled receptors activates PLC beta hydrolyzing PI45P2 releasing IP3 diffuses ER binding IP3R calcium channels raising cytosolic calcium one hundred nanomolar to micromolar activating calmodulin calcineurin CaMK and DAG remaining membrane activating PKC RasGRP protein kinase D. RTK activation recruits PI3K phosphorylating PI45P2 PIP3 recruiting Akt PDK1 via PH domains promoting survival growth via mTOR S6K inhibiting apoptosis BAD. Phosphatidylcholine mainly structural donor SM de novo glycerolipid, ganglioside recognition toxin receptors GM1 cholera tetanus, cholesterol fluidity buffer rigidity no direct second messenger generation. Thus PI cycle couples extracellular cues calcium kinase cytoskeletal remodeling central learning memory insulin signaling cancer signaling questions NEET CSIR NET GATE core signaling module essential understanding pathway integration and feedback loops.