Phosphoinositides and the endocytic pathway.

Phosphorylation of the phosphatidylinositol headgroup generates seven varieties of phosphoinositide of which PtdIns(4,5)P(2), PtdIns3P and PtdIns (3,5)P(2) have established roles on the endocytic pathway. In this review, we discuss the enzymes responsible for generation and turnover of these lipids, which are keys to determining compartmental identity and the flux of material through the endocytic system. The enzymatic generation of lipids serves as an amplification mechanism through which a wide variety of effector molecules can be recruited.