Phosphatidylinositol 3-phosphate

Phosphatidylinositol 3-phosphate (PtdIns3P) is the product of both the class II and III phosphoinositide 3-kinases (PI 3-kinases) activity on Phosphatidylinositol.

PtdIns3P is dephophosphorylated by the myotubularin family of phosphatases, on the D3 position of the inositol ring.

The FYVE domain, and the PX domain in a number of proteins binds to PtdIns3P include those in SNX1, Hrs, and EEA1.

The majority of PtdIns3P appears to be constitutively synthesised by the class III PI 3-kinase, Vps34 at endocytic membranes. Class II PI 3-kinases also appear to synthesise PtdIns3P, their activity however appears to be regulated by a range of stimuli, including growth factors. This suggests that specific pools of PtdIns3P may be synthesised upon cell stimulation.

PtdIns3P in cell membranes helps to recruit a range of proteins, many of which are involved in protein trafficking.