At the early endosome membrane, phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) is generated in two steps from phosphatidylinositol 3,4-bisphosphate PI(3,4)P2 by the action of various kinases and phosphatases (Sbrissa et al. 2007, Sbrissa et al. 2008, Cao et al. 2007, Cao et al. 2008, Arcaro et al. 2000, Kim et al. 2002).