The pivotal role of phosphatidylinositol 3-kinase (PI 3-kinase) in signal transduction has been well established in recent years. Receptor-regulated forms of PI 3-kinase are thought to phosphorylate phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) at the 3-position of the inositol ring to give the putative lipid second messenger, phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4, 5)P3)....

Identification of a G protein-coupled receptor activated by UDP-glucose led us to develop a sensitive and specific assay for UDP-glucose mass and to test whether this sugar nucleotide is released as an extracellular signaling molecule. Mechanical stimulation of 1321N1 human astrocytoma cells by a change of medium resulted in an increase in extracellular levels of both ATP and UDP-glucose. Where...

The basal (swelling-induced) and receptor-stimulated effluxes of I and taurine have been monitored to determine whether these two osmolytes are released from human SH-SY5Y cells under hypotonic conditions via common or distinct mechanisms. Under basal conditions, both I (used as a tracer for Cl ) and taurine were released from the cells in a volumedependent manner. The addition of thrombin, med...