Phosphatidylinositol Phosphate (PIP)

Phosphatidylinositol 3-phosphate is a phospholipid found in cell membranes that helps to recruit a range of proteins, many of which are involved in protein trafficking, to the membranes. It is the product of both the class II and III phosphoinositide 3-kinases (PI 3-kinases) activity on phosphatidylinositol. Phosphatidylinositol 4-phosphate is a precursor of Phosphatidylinositol (4,5)-bisphosphate. PtdIns4P is prevalent in the membrane of the Golgi apparatus.In the Golgi apparatus, PtdIns4P binds to the GTP-binding protein ARF and to effector proteins, including four-phosphate-adaptor protein 1 and 2 (FAPP1 and FAPP2). This three molecule complex recruits proteins that need to be carried to the cell membrane. Phosphatidylinositol 5-phosphate is one of the seven phosphoinositides, and is the last to have been discovered to be naturally occurring.