1-(1,2R-DIHEXADECANOYLPHOSPHATIDYL)INOSITOL-3,4,5-TRIPHOSPHATE, HEXASODIUM SALT

The phosphatidylinositol phosphates represent a small percentage of total membrane phospholipids. However, they play a critical role in the generation and transmission of cellular signals.^1,2 PtdIns-(3,4,5)-P₃ can serve as an anchor for the binding of signal transduction proteins bearing pleckstrin homology (PH) domains. Centuarin α and the Akt-family of GTPase activating proteins are examples of PtdIns-(3,4,5)-P₃-binding proteins.^3,4 Protein-binding to PtdIns-(3,4,5)-P₃ is important for cytoskeletal rearrangements and membrane trafficking. PtdIns-(3,4,5)-P₃ is resistant to cleavage by PI-specific phospholipase C (PLC). Thus, it is likely to function in signal transduction as a modulator in its own right, rather than as a source of inositol tetraphosphates. For further reading on inositol phospholipids, see also references ⁵ and ⁶.

1. Lapetina, E.G., Billah, M.M., and Cuatrecasas, P. The phosphatidylinositol cycle and the regulation of arachidonic acid production Nature 292,367-369(1981).
2. Majerus, P.W. Inositol phosphate biochemistry Annu. Rev. Biochem. 61,225-250(1992).
3. Tanaka, K., Imajoh-Ohmi, S., Sawada, T., et al. A target of phosphatidylinositol 3,4,5-trisphosphate with a zinc finger motif similar to that of the ADP-ribosylation-factor GTPase-activating protein and two pleckstrin homology domains Eur. J. Biochem. 245,512-519(1997).
4. Yang, X., Rudolf, M., Carew, M.A., et al. Inositol 1,3,4-trisphosphate acts in vivo as a specific regulator of cellular signaling by inositol 3,4,5,6-tetrakisphosphate J. Biol. Chem. 274(27),18973-18980(1999).
5. Pike, L.J., and Casey, L. Localization and turnover of phosphatidylinositol 4,5-bisphosphate in caveolin-enriched membrane domains J. Biol. Chem. 271,26453-26456(1996).
6. Berridge, M.J. Inositol trisphosphate and calcium signalling Nature 361(6410),315-325(1993).