PI4P is dephosphorylated to PI by SACM1L at the ER membrane

At the endoplasmic reticulum (ER) membrane, transmembrane protein phosphatidylinositide phosphatase SAC1 (SACM1L) efficiently dephosphorylates phosphatidylinositol 4-phosphate (PI4P), and to a lesser extent phosphatidylinositol 3-phosphate (PI3P), to phosphatidylinositol (PI). No significant activity of this enzyme towards phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) was detected (Rohde et al. 2003).

在内质网（ER）膜上，跨膜蛋白磷脂酰肌醇磷酸酶SAC1（SACM1L）高效地将磷脂酰肌醇4-磷酸（PI4P）去磷酸化，至一定程度亦能去磷酸化磷脂酰肌醇3-磷酸（PI3P），转化为磷脂酰肌醇（PI）。然而，该酶对磷脂酰肌醇3,5-二磷酸（PI(3,5)P2）并无显著活性（Rohde等，2003年）。