PI is phosphorylated to PI4P by PI4KA/2B at the ER membrane At the endoplasmic reticulum (ER) membrane, phosphatidylinositol 4-kinase alpha (PI4KA) (Wong et al. 1997, Gehrmann et al. 1999) or phosphatidylinositol 4-kinase type 2-beta (PI4K2B) (Wei et al. 2002) phosphorylate phosphatidylinositol (PI) to produce phosphatidylinositol 4-phosphate (PI4P). Authored: Williams, MG, 2011-10-18 EC Number: 2.7.1.67 Edited: Williams, MG, 2011-08-12 Pubmed10101268 Pubmed12324459 Pubmed9148941 Reactome Database ID Release 431675813 Reactome, http://www.reactome.org ReactomeREACT_121159 Reviewed: Wakelam, Michael, 2012-05-14