Module 2: Figure phosphoinositide signalling systems
PtdIns metabolism spawns a variety of signalling cassettes.
The metabolism of PtdIns creates a number of lipid and inositol phosphate derivatives that operate a variety of signalling cassettes. PtdIns4,5P2 is a nodal point for a number of signalling cassettes. It is the precursor that is hydrolysed to generate the second messengers inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG). It is phosphorylated further to form the lipid second messenger PtdIns3,4,5P3. The localized turnover of PtdIns4,5P2 also has a signalling role within the PtdIns4,5P2 signalling cassette that regulates a variety of processes such as the cytoskeleton, control of the processes of membrane trafficking and exocytosis and the regulation of ion channels and exchangers. Finally, the InsP3 enters a complex pathway of inositol phosphate metabolism that generates components of the multipurpose inositol polyphosphate signalling cassette.