EC:3.1.3.62 xrefs

[sjm41]

EC:3.1.3.62 Name: multiple inositol-polyphosphate phosphatase Alt names: inositol (1,3,4,5)-tetrakisphosphate 3-phosphatase, inositol-1,3,4,5-tetrakisphosphate 3-phosphatase, inositol 1,3,4,5-tetrakisphosphate 3-phosphomonoesterase, inositol 1,3,4,5-tetrakisphosphate-5-phosphomonoesterase, inositol tetrakisphosphate phosphomonoesterase, MIPP Reaction: myo-inositol hexakisphosphate + H2O <=> myo-inositol pentakisphosphate (mixed isomers) + phosphate Comments: Also acts on Ins(1,3,4,5)P4 to yield Ins(1,4,5)P3.

This EC is currently an xref on these two parent-and-child terms:

id: GO:0004446 name: inositol-hexakisphosphate phosphatase activity def: "Catalysis of the reaction: myo-inositol hexakisphosphate + H2O = myo-inositol pentakisphosphate (mixed isomers) + phosphate." [EC:3.1.3.62] xref: EC:3.1.3.62 xref: MetaCyc:RXN-7920 is_a: GO:0052745 ! inositol phosphate phosphatase activity

id: GO:0052826 name: inositol hexakisphosphate 2-phosphatase activity def: "Catalysis of the reaction: myo-inositol hexakisphosphate + H2O = myo-inositol 1,3,4,5,6-pentakisphosphate + phosphate." [EC:3.1.3.62] xref: EC:3.1.3.62 is_a: GO:0004446 ! inositol-hexakisphosphate phosphatase activity

From the EC:3.1.3.62 comment and alt names, it should also be an xref on the related GO:0051717 term:

id: GO:0051717 name: inositol-1,3,4,5-tetrakisphosphate 3-phosphatase activity def: "Catalysis of the reaction: inositol-1,3,4,5-tetrakisphosphate + H2O = inositol-1,4,5-trisphosphate + phosphate." [GOC:bf, MetaCyc:3.1.3.62-RXN] synonym: "inositol (1,3,4,5)-tetrakisphosphate 3-phosphatase activity" RELATED [EC:2.7.1.-] synonym: "inositol 1,3,4,5-tetrakisphosphate 3-phosphomonoesterase activity" RELATED [EC:2.7.1.-] synonym: "inositol 1,3,4,5-tetrakisphosphate-5-phosphomonoesterase activity" RELATED [EC:2.7.1.-] xref: MetaCyc:3.1.3.62-RXN is_a: GO:0052743 ! inositol tetrakisphosphate phosphatase activity

Also, it's odd that the synonyms on GO:0051717 are attributed to 'EC:2.7.1.-' (= Phosphotransferases with an alcohol group as acceptor) - that doesn't make sense...

[sjm41]

Also, should remove the hyphen from "inositol-hexakisphosphate phosphatase activity" (GO:0004446) to be consistent with sister terms: GO:0046030 inositol trisphosphate phosphatase activity GO:0052743 inositol tetrakisphosphate phosphatase activity GO:0016312 inositol bisphosphate phosphatase activity GO:0052834 inositol monophosphate phosphatase activity GO:0004446 inositol-hexakisphosphate phosphatase activity GO:0052827 inositol pentakisphosphate phosphatase activity

[kaxelsen]

I have just updated the EC 3.1.3.62 entry at IUBMB. The updated entry is currently in progress in the IUBMB system, so it will take some time before the changes will become public.

name: multiple inositol-polyphosphate phosphatase alt name: MIPP; phytase (ambiguous); 1D-myo-inositol-hexakisphosphate 5-phosphohydrolase (incorrect) reactions: (1) myo-inositol hexakisphosphate + H2O = 1D-myo-inositol 1,2,4,5,6-pentakisphosphate + phosphate (2) 1D-myo-inositol 1,2,4,5,6-pentakisphosphate + H2O = 1D-myo-inositol 1,2,5,6-tetrakisphosphate + phosphate (3) 1D-myo-inositol 1,2,5,6-tetrakisphosphate + H2O = 1D-myo-inositol 1,2,6-trisphosphate + phosphate (4) 1D-myo-inositol 1,2,6-trisphosphate + H2O = 1D-myo-inositol 1,2-bisphosphate + phosphate (5) 1D-myo-inositol 1,2-bisphosphate + H2O = 1D-myo-inositol 2-phosphate + phosphate Comments: This ubiquitous enzyme degrades myo-inositol hexakisphosphate (phytate) to Ins(2,3)P2 and Ins(2)P. Activities have been characterized in the yeast Saccharomyces cerevisiae [2], the plant Lupinus albus [3] and the bacteria Bacillus sp. [4] and Raoultella terrigena [5]. In mammal cells Ins(2,3)P2 and Ins(2)P are the major inositol phosphate compounds found [6]. The mammal enzyme is also active on Ins(1,3,4,5,6)P5 that is dephosphorylated to Ins(1,4,5,6)P4 and Ins(1,4,5)P3, and on 2,3-bisphospho-D-glycerate (cf. EC 3.1.3.80, 2,3-bisphosphoglycerate 3-phosphatase). In addition, it acts on Ins(1,3,4,5)P4 to yield Ins(1,4,5)P3 in vitro (cf. EC 3.1.3.67, phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase) [7]. It does not hydrolyse phosphates from the 2-positions of inositol phosphates [6]. In other organisms the degradation of phytate follows different routes. (cf. EC 3.1.3.8, 3-phytase, EC 3.1.3.26, 4-phytase, and EC 3.1.3.72, 5-phytase). Refs: 9359836, 11368581, 12405789, 12556126, 16917535, 36589890, 37371464

An important point is that MINPP1 is found in the ER, while PTEN (EC 3.1.3.67) is found in the cytosol. It is still unknown how the MINPP1 meets its inositol phosphate substrates, as the inositols are also believed to be in the cytosol.

[sjm41]

Thanks @kaxelsen ! So this EC covers many individual reactions, and so doesn't map 1:1 to any GO activity term. Based on the revised EC entry, I'd suggest we:

• [ ] either (i) not add the EC 3.1.3.62 xref to any GO terms (since it represents several activities), or (ii) create all the individual reactions listed in the revised EC def (none of reactions 1-5 appear to be in the current GO?) and add EC 3.1.3.62 as a narrow xref to all of them

• [ ] modify the GO:0004446 inositol-hexakisphosphate phosphatase activity def to match that of all its sister (=grouping) terms, ie "Catalysis of the reaction: myo-inositol hexakisphosphate + H2O = myo-inositol pentakisphosphate + phosphate." and remove the EC 3.1.3.62 xref

• [ ] obsolete the child GO:0052826 inositol hexakisphosphate 2-phosphatase activity, since this reaction doesn't seem to be covered by the EC 3.1.3.62 description at all (and there's no EXP annotations to that GO term)