The Enzyme Database

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EC 2.7.7.74     
Accepted name: 1L-myo-inositol 1-phosphate cytidylyltransferase
Reaction: CTP + 1L-myo-inositol 1-phosphate = diphosphate + CDP-1L-myo-inositol
For diagram of bis(1L-myo-inositol) 1,3′-phosphate biosynthesis, click here
Glossary: 1L-myo-inositol 1-phosphate = 1D-myo-inositol 3-phosphate
Other name(s): CTP:inositol-1-phosphate cytidylyltransferase (bifunctional CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase (IPCT/DIPPS)); IPCT (bifunctional CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase (IPCT/DIPPS)); L-myo-inositol-1-phosphate cytidylyltransferase
Systematic name: CTP:1L-myo-inositol 1-phosphate cytidylyltransferase
Comments: In many organisms this activity is catalysed by a bifunctional enzyme. The cytidylyltransferase domain of the bifunctional EC 2.7.7.74/EC 2.7.8.34 (CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase) is absolutely specific for CTP and 1L-myo-inositol 1-phosphate. The enzyme is involved in biosynthesis of bis(1L-myo-inositol) 1,3′-phosphate, a widespread organic solute in microorganisms adapted to hot environments.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Rodrigues, M.V., Borges, N., Henriques, M., Lamosa, P., Ventura, R., Fernandes, C., Empadinhas, N., Maycock, C., da Costa, M.S. and Santos, H. Bifunctional CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase, the key enzyme for di-myo-inositol-phosphate synthesis in several (hyper)thermophiles. J. Bacteriol. 189 (2007) 5405–5412. [DOI] [PMID: 17526717]
[EC 2.7.7.74 created 2011]
 
 
EC 2.7.8.34     
Accepted name: CDP-L-myo-inositol myo-inositolphosphotransferase
Reaction: CDP-1L-myo-inositol + 1L-myo-inositol 1-phosphate = CMP + bis(1L-myo-inositol) 3,1′-phosphate 1-phosphate
For diagram of bis(1L-myo-inositol) 1,3′-phosphate biosynthesis, click here
Glossary: 1L-myo-inositol 1-phosphate = 1D-myo-inositol 3-phosphate
Other name(s): CDP-inositol:inositol-1-phosphate transferase (bifunctional CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase (IPCT/DIPPS)); DIPPS (bifunctional CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase (IPCT/DIPPS))
Systematic name: CDP-1L-myo-inositol:1L-myo-inositol 1-phosphate myo-inositolphosphotransferase
Comments: In many organisms this activity is catalysed by a bifunctional enzyme. The di-myo-inositol-1,3′-phosphate-1′-phosphate synthase domain of the bifunctional EC 2.7.7.74/EC 2.7.8.34 (CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase) uses only 1L-myo-inositol 1-phosphate as an alcohol acceptor, but CDP-glycerol, as well as CDP-1L-myo-inositol and CDP-D-myo-inositol, are recognized as alcohol donors. The enzyme is involved in biosynthesis of bis(1L-myo-inositol) 1,3-phosphate, a widespread organic solute in microorganisms adapted to hot environments.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Rodrigues, M.V., Borges, N., Henriques, M., Lamosa, P., Ventura, R., Fernandes, C., Empadinhas, N., Maycock, C., da Costa, M.S. and Santos, H. Bifunctional CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase, the key enzyme for di-myo-inositol-phosphate synthesis in several (hyper)thermophiles. J. Bacteriol. 189 (2007) 5405–5412. [DOI] [PMID: 17526717]
[EC 2.7.8.34 created 2011]
 
 
EC 2.7.8.39     
Accepted name: archaetidylinositol phosphate synthase
Reaction: CDP-2,3-bis-(O-phytanyl)-sn-glycerol + 1L-myo-inositol 1-phosphate = CMP + 1-archaetidyl-1D-myo-inositol 3-phosphate
Glossary: 1L-myo-inositol 1-phosphate = 1D-myo-inositol 3-phosphate
CDP-2,3-bis-(O-phytanyl)-sn-glycerol = CDP-2,3-di-(O-phytanyl)-sn-glycerol = CDP-archaeol
1-archaetidyl-1D-myo-inositol 3-phosphate = archaetidyl-myo-inositol 1-phosphate
Other name(s): AIP synthase
Systematic name: CDP-2,3-bis-(O-phytanyl)-sn-glycerol:1L-myo-inositol 1-phosphate 1-sn-archaetidyltransferase
Comments: Requires Mg2+ or Mn2+ for activity. The enzyme is involved in biosynthesis of archaetidyl-myo-inositol, a compound essential for glycolipid biosynthesis in archaea.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Morii, H., Kiyonari, S., Ishino, Y. and Koga, Y. A novel biosynthetic pathway of archaetidyl-myo-inositol via archaetidyl-myo-inositol phosphate from CDP-archaeol and D-glucose 6-phosphate in methanoarchaeon Methanothermobacter thermautotrophicus cells. J. Biol. Chem. 284 (2009) 30766–30774. [DOI] [PMID: 19740749]
[EC 2.7.8.39 created 2013]
 
 
EC 3.1.3.25     
Accepted name: inositol-phosphate phosphatase
Reaction: myo-inositol phosphate + H2O = myo-inositol + phosphate
For diagram of myo-inositol biosynthesis, click here
Other name(s): myo-inositol-1(or 4)-monophosphatase; inositol 1-phosphatase; L-myo-inositol-1-phosphate phosphatase; myo-inositol 1-phosphatase; inositol phosphatase; inositol monophosphate phosphatase; inositol-1(or 4)-monophosphatase; myo-inositol-1(or 4)-phosphate phosphohydrolase; myo-inositol monophosphatase; myo-inositol-1-phosphatase
Systematic name: myo-inositol-phosphate phosphohydrolase
Comments: Acts on five of the six isomers of myo-inositol phosphate, all except myo-inositol 2-phosphate, but does not act on myo-inositol bearing more than one phosphate group. It also acts on adenosine 2′-phosphate (but not the 3′- or 5′- phosphates), sn-glycerol 3-phosphate and glycerol 2-phosphate. Two isoforms are known [4].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 37184-63-7
References:
1.  Eisenberg, F., Jr. D-Myoinositol 1-phosphate as product of cyclization of glucose 6-phosphate and substrate for a specific phosphatase in rat testis. J. Biol. Chem. 242 (1967) 1375–1382. [PMID: 4290245]
2.  Gee, N.S., Ragan, C.I., Watling, K.J., Aspley, S., Jackson, R.G., Reid, G.G., Gani, D. and Shute, J.K. The purification and properties of myo-inositol monophosphatase from bovine brain. Biochem. J. 249 (1988) 883–889. [PMID: 2833231]
3.  Hallcher, L.M. and Sherman, W.R. The effects of lithium ion and other agents on the activity of myo-inositol-1-phosphatase from bovine brain. J. Biol. Chem. 255 (1980) 10896–10901. [PMID: 6253491]
4.  Yoshikawa, T., Turner, G., Esterling, L.E., Sanders, A.R. and Detera-Wadleigh, S.D. A novel human myo-inositol monophosphatase gene, IMP.18p, maps to a susceptibility region for bipolar disorder. Mol. Psychiatry 2 (1997) 393–397. [PMID: 9322233]
5.  Woscholski, R. and Parker, P.J. Inositol phosphatases: constructive destruction of phosphoinositides and inositol phosphates. In: Cockcroft, S. (Ed.), Biology of Phosphoinositides, Biology of Phosphoinositides, Oxford, 2000, pp. 320–338.
6.  Ackermann, K.E., Gish, B.G., Honchar, M.P. and Sherman, W.R. Evidence that inositol 1-phosphate in brain of lithium-treated rats results mainly from phosphatidylinositol metabolism. Biochem. J. 242 (1987) 517–524. [PMID: 3036092]
[EC 3.1.3.25 created 1972, modified 1990, modified 2002, modified 2004]
 
 
EC 3.1.3.57     
Accepted name: inositol-1,4-bisphosphate 1-phosphatase
Reaction: 1D-myo-inositol 1,4-bisphosphate + H2O = 1D-myo-inositol 4-phosphate + phosphate
For diagram of myo-inositol-phosphate biosynthesis, click here
Other name(s): inositol-polyphosphate 1-phosphatase
Systematic name: 1D-myo-inositol-1,4-bisphosphate 1-phosphohydrolase
Comments: The enzyme acts on inositol 1,4-bisphosphate and inositol 1,3,4-trisphosphate (forming inositol 3,4-bisphosphate) with similar Vmax values for both substrates, but with a five-times higher affinity for the bisphosphate. Does not act on inositol 1-phosphate, inositol 1,4,5-trisphosphate or inositol 1,3,4,5-tetrakisphosphate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 111070-17-8, 111694-13-4
References:
1.  Berridge, M.J., Dawson, R.M.C., Downes, C.P., Heslop, J.P. and Irvine, R.F. Changes in the levels of inositol phosphates after agonist-dependent hydrolysis of membrane phosphoinositides. Biochem. J. 212 (1983) 473–482. [PMID: 6309146]
2.  Connolly, T.M., Bansal, V.S., Bross, T.E., Irvine, R.F. and Majerus, P.W. The metabolism of tris- and tetraphosphates of inositol by 5-phosphomonoesterase and 3-kinase enzymes. J. Biol. Chem. 262 (1987) 2146–2149. [PMID: 3029066]
3.  Inhorn, R.C. and Majerus, P.W. Inositol polyphosphate 1-phosphatase from calf brain. Purification and inhibition by Li+, Ca2+, and Mn2+. J. Biol. Chem. 262 (1987) 15946–15952. [PMID: 2824473]
[EC 3.1.3.57 created 1989, modified 2002]
 
 
EC 3.1.3.64     
Accepted name: phosphatidylinositol-3-phosphatase
Reaction: 1-phosphatidyl-1D-myo-inositol 3-phosphate + H2O = 1-phosphatidyl-1D-myo-inositol + phosphate
For diagram of 1-phosphatidyl-myo-inositol metabolism, click here
Glossary: inositol 1-phosphate = Ins-1-P
inositol 1,3-bisphosphate = Ins(1,3)P2
1-phosphatidyl-1D-myo-inositol = PtdIns
1-phosphatidyl-1D-myo-inositol 3-phosphate = PtdIns3P
Other name(s): inositol-1,3-bisphosphate 3-phosphatase; inositol 1,3-bisphosphate phosphatase; inositol-polyphosphate 3-phosphatase; D-myo-inositol-1,3-bisphosphate 3-phosphohydrolase; phosphatidyl-3-phosphate 3-phosphohydrolase
Systematic name: 1-phosphatidyl-1D-myo-inositol-3-phosphate 3-phosphohydrolase
Comments: This enzyme still works when the 2,3-bis(acyloxy)propyl group is removed, i.e., it hydrolyses Ins(1,3)P2 to Ins-1-P.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 124248-47-1
References:
1.  Lips, D.L. and Majerus, P.W. The discovery of a 3-phosphomonoesterase that hydrolyzes phosphatidylinositol 3-phosphate in NIH 3T3 cells. J. Biol. Chem. 264 (1989) 19911–19915. [PMID: 2555336]
2.  Caldwell, K.K., Lips, D.L., Bansal, V.S. and Majerus, P.W. Isolation and characterization of two 3-phosphatases that hydrolyze both phosphatidylinositol 3-phosphate and inositol 1,3-bisphosphate. J. Biol. Chem. 266 (1991) 18378–18386. [PMID: 1655747]
[EC 3.1.3.64 created 1992, [EC 3.1.3.65 created 1992, incorporated 2002], modified 2002]]
 
 
EC 3.1.4.43     
Accepted name: glycerophosphoinositol inositolphosphodiesterase
Reaction: 1-(sn-glycero-3-phospho)-1D-myo-inositol + H2O = glycerol + 1D-myo-inositol 1-phosphate
For diagram of 1-(glycero-3-phospho)-myo-inositol catabolism, click here
Other name(s): 1,2-cyclic-inositol-phosphate phosphodiesterase; D-myo-inositol 1:2-cyclic phosphate 2-phosphohydrolase; D-inositol 1,2-cyclic phosphate 2-phosphohydrolase; D-myo-inositol 1,2-cyclic phosphate 2-phosphohydrolase; 1-D-myo-inositol-1,2-cyclic-phosphate 2-inositolphosphohydrolase; inositol-1,2-cyclic-phosphate 2-inositolphosphohydrolase
Systematic name: 1-(sn-glycero-3-phospho)-1D-myo-inositol inositolphosphohydrolase
Comments: This enzyme also hydrolyses Ins(cyclic1,2)P to Ins-1-P
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9076-91-9 (from EC 3.1.4.36), 72414-13-2 (not distinguished from EC 3.1.4.44)
References:
1.  Dawson, R.M.C. and Hemington, N. A phosphodiesterase in rat kidney cortex that hydrolyses glycerylphosphorylinositol. Biochem. J. 162 (1977) 241–245. [PMID: 192216]
2.  Dawson, R.M.C. and Clarke, N.G. D-myoInositol 1:2-cyclic phosphate 2-phosphohydrolase. Biochem. J. 127 (1972) 113–118. [PMID: 4342209]
3.  Dawson, R.M.C. and Clarke, N.G. A comparison of D-inositol 1:2-cyclic phosphate 2-phosphohydrolase with other phosphodiesterases of kidney. Biochem. J. 134 (1973) 59–67. [PMID: 4353088]
4.  Ross, T.S. and Majerus, P.W. Inositol-1,2-cyclic-phosphate 2-inositolphosphohydrolase. Substrate specificity and regulation of activity by phospholipids, metal ion chelators, and inositol 2-phosphate. J. Biol. Chem. 266 (1991) 851–856. [PMID: 1845995]
[EC 3.1.4.43 created 1984, (EC 3.1.4.36 created 1976, incorporated 2002), modified 2002]
 
 
EC 5.5.1.4     
Accepted name: inositol-3-phosphate synthase
Reaction: D-glucose 6-phosphate = 1D-myo-inositol 3-phosphate
For diagram of myo-inositol biosynthesis, click here and for mechanism of reaction, click here
Other name(s): myo-inositol-1-phosphate synthase; D-glucose 6-phosphate cycloaldolase; inositol 1-phosphate synthatase; glucose 6-phosphate cyclase; inositol 1-phosphate synthetase; glucose-6-phosphate inositol monophosphate cycloaldolase; glucocycloaldolase; 1L-myo-inositol-1-phosphate lyase (isomerizing)
Systematic name: 1D-myo-inositol-3-phosphate lyase (isomerizing)
Comments: Requires NAD+, which dehydrogenates the -CHOH- group to -CO- at C-5 of the glucose 6-phosphate, making C-6 into an active methylene, able to condense with the -CHO at C-1. Finally, the enzyme-bound NADH reconverts C-5 into the -CHOH- form.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9032-95-5
References:
1.  Eisenberg, F., Jr. D-Myoinositol 1-phosphate as product of cyclization of glucose 6-phosphate and substrate for a specific phosphatase in rat testis. J. Biol. Chem. 242 (1967) 1375–1382. [PMID: 4290245]
2.  Sherman, W.R., Stewart, M.A. and Zinbo, M. Mass spectrometric study on the mechanism of D-glucose 6-phosphate-L-myo-inositol 1-phosphate cyclase. J. Biol. Chem. 244 (1969) 5703–5708. [PMID: 4310603]
3.  Barnett, J.E.G. and Corina, D.L. The mechanism of glucose 6-phosphate-D-myo-inositol 1-phosphate cyclase of rat testis. The involvement of hydrogen atoms. Biochem. J. 108 (1968) 125–129. [PMID: 4297937]
4.  Barnett, J.E.G., Rasheed, A. and Corina, D.L. Partial reactions of glucose 6-phosphate-1L-myo-inositol 1-phosphate cyclase. Biochem. J. 131 (1973) 21–30. [PMID: 4352864]
[EC 5.5.1.4 created 1972, modified 2001]
 
 


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