At the plasma membrane, phosphatidylinositol-4-phosphate 5-kinase type-1 alpha (PIP5K1A), beta (PIP5K1B), and gamma (PIP5K1C) phosphorylate phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2) to produce phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3). This is a minor reaction, however, and its physiological role is uncertain.
The following lists the above proteins with their corresponding literature references: PIP5K1A (Zhang et al. 1997, Tolias et al. 1998), PIP5K1B (Zhang et al. 1997, Tolias et al. 1998), and PIP5K1C (Wenk et al. 2001, Di Paolo et al. 2002, Krauss et al. 2003).