The regulation of phosphoinositide phosphorylation was studied in Swiss 3T3 cells that were stimulated by platelet-derived growth factor (PDGF). Studies with intact cells showed that the mitogen increased the incorporation of 32P into phosphatidylinositol (PtdIns), phosphatidylinositol 4-phosphate (PtdIns-P), and phosphatidylinositol 4,5-bisphosphate (PtdIns-P2) during the cell cycle, with dist...

The Fab1 protein is a phosphatidylinositol 3-phosphate 5-kinase involved in yeast stress response and membrane trafficking. New evidence indicates that the Vac14 protein, like Vac7p, regulates phosphatidylinositol 3,5-bisphosphate levels and possibly Fab1p activity.

The four mammalian phosphatidylinositol 4-kinases modulate inter-organelle lipid trafficking, phosphoinositide signalling and intracellular vesicle trafficking. In addition to catalytic domains required for the synthesis of PI4P, the phosphatidylinositol 4-kinases also contain isoform-specific structural motifs that mediate interactions with proteins such as AP-3 and the E3 ubiquitin ligase Itc...