Rethinking phosphatidylinositol 3-monophosphate

A generally accepted view considers phosphatidylinositol 3-monophosphate (PtdIns3P) as a lipid confined to the endosomal compartment where it regulates trafficking pathways and is produced constitutively and exclusively by class III phosphoinositide 3-kinase (PI3K). Recent evidence suggests that this phosphoinositide has a more complex role as a second messenger involved in different physiological and pathological events and that specific intracellular localization of kinases and/or phosphatases is critical for PtdIns3P synthesis and PtdIns3P-dependent intracellular functions. Here, we review the current knowledge of the regulation and function of PtdIns3P and discuss how the view of PtdIns3P changed in the last few years. (C) 2009 Elsevier B.V. All rights reserved.