Liu, Y., Casey, L. and Pike, L.J. (1998) Compartmentalization of Phosphatidylinositol 4,5-Bisphosphate in Low-Density Membrane Domains in the Absence of Caveolin. Biochem. Biophys. Res. Commun. 245: 684-690.

In cells that exhibit caveolae, the hormone-sensitive pool of PtdIns PtdIns 4,5-P2 is localized in a low density, caveolin-enriched membrane fraction. Neuro 2a cells do not express caveolin. Nonetheless, the PtdIns 4,5-P2 in these cells is compartmentalized in a low density, detergent-insoluble domain that also contains other signaling-related molecules. Compartmentalization of PtdIns PtdIns 4,5-P2 was observed regardless of whether Triton X-100-containing or detergent-free methods were used to prepare the membranes. However, the partitioning of receptor tyrosine kinases and GPI-anchored proteins into the low density domains was dependent upon the method of membrane preparation. Treatment of Neruo 2a cells with cyclodextrin delocalized the PtdIns PtdIns 4,5-P2 and inhibited hormone-stimulated PtdIns turnover. These results suggest that compartmentalization of PtdIns PtdIns 4,5-P2 does not require caveolin but is necessary for the proper functioning of phosphoinositide-based signaling.