Background：Phosphorylated derivatives of phosphatidylinositol （PtdIns） regulate cytoskeletal functions, membrane trafficking, and receptor signaling by recruiting protein complexes to cell- and endosomal-membranes. Humans have multiple PtdIns proteins that differ by the degree and position of phosphorylation of the inositol ring. This gene encodes an enzyme （PIKfyve; also known as phosphatidylinositol-3-phosphate 5-kinase type III or PIPKIII） that phosphorylates the D-5 position in PtdIns and phosphatidylinositol-3-phosphate （PtdIns3P） to make PtdIns5P and PtdIns（3,5）biphosphate.
