I(1,3,4,5)P4 is dephosphorylated to I(1,3,4)P3 by INPP5[3]/ITPK1 in the cytosol A group of inositol phosphatases and the broad specificity enzyme inositol-tetrakisphosphate 1-kinase (ITPK1) dephosphorylate inositol 1,3,4,5-tetrakisphosphate (I(1,3,4,5)P4) to inositol 1,3,4-trisphosphate (I(1,3,4)P3). The group of inositol phosphatases involved are: inositol polyphosphate 5-phosphatase OCRL-1 (OCRL), phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 1 (INPP5D) aka SHIP1, phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 2 (INPPL1) aka SHIP2, phosphatidylinositol 4,5-bisphosphate 5-phosphatase A (INPP5J) aka PIPP, and synaptic inositol-1,4,5-trisphosphate 5-phosphatase 1 (SYNJ1).<br><br>The following lists the above proteins with their corresponding literature references: OCRL (Chang et al. 2002, Zhang et al. 1995, Zhang et al. 1998, Schmid et al. 2004); INPP5D (Drayer et al. 1996, Kavanaugh et al. 1996); INPPL1 (Chi et al. 2004); INPP5J (Mochizuki & Thompson 1999); SYNJ1 (Schmid et al. 2004); ITPK1 (Ho et al. 2002). Authored: Williams, MG, 2011-10-28 EC Number: 3.1.3.56 Edited: Williams, MG, 2011-10-28 Pubmed10593988 Pubmed11909533 Pubmed12223481 Pubmed15316017 Pubmed15474001 Pubmed7761412 Pubmed8723348 Pubmed8769125 Pubmed9430698 Reactome Database ID Release 431855218 Reactome, http://www.reactome.org ReactomeREACT_150220 Reviewed: Challiss, John, 2012-11-09