MetaCyc Enzyme: inositol-1-phosphate synthase

Gene: AF1794 Accession Number: G-3884 (MetaCyc)

Species: Archaeoglobus fulgidus

Subunit composition of inositol-1-phosphate synthase = [AF1794]4
         inositol-1-phosphate synthase subunit = AF1794

The Archaeoglobus fulgidus inositol-1-phosphate synthase (IPS) gene was overexpressed in Escherichia coli. This archaeal enzyme, with the highest activity at its optimum growth temperature among all IPS reported, is extremely heat stable. The most unique feature of the Archaeoglobus fulgidus enzyme is that it absolutely requires divalent metal ions for activity, while NH4+ (a critical activator for all the other characterized IPS enzymes) has no effect. These properties suggested that this archaeal IPS is a class II aldolase [Chen00c].

Molecular Weight of Polypeptide: 44 kD (experimental) [Chen00c ]

Molecular Weight of Multimer: 168 kD (experimental) [Chen00c]

Unification Links: ModBase:O28480 , Protein Model Portal:O28480 , SMR:O28480 , String:224325.AF1794 , Swiss-Model:O28480 , UniProt:O28480

Relationship Links: Entrez-Nucleotide:PART-OF:AE000979 , InterPro:IN-FAMILY:IPR002587 , InterPro:IN-FAMILY:IPR013021 , InterPro:IN-FAMILY:IPR016040 , Panther:IN-FAMILY:PTHR11510 , PDB:Structure:1U1I , PDB:Structure:3QVS , PDB:Structure:3QVT , PDB:Structure:3QVW , PDB:Structure:3QVX , PDB:Structure:3QW2 , Pfam:IN-FAMILY:PF01658 , Pfam:IN-FAMILY:PF07994

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Instance reaction of [D-glucopyranose 6-phosphate → 1D-myo-inositol 3-monophosphate] (
i1: β-D-glucose 6-phosphate = 1D-myo-inositol 3-monophosphate (

MultiFun Terms: metabolism biosynthesis of macromolecules (cellular constituents) phospholipid

Enzymatic reaction of: inositol-1-phosphate synthase

EC Number:

D-glucopyranose 6-phosphate <=> 1D-myo-inositol 3-monophosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: myo-inositol biosynthesis , di-myo-inositol phosphate biosynthesis

Activators (Allosteric): Zn2+ [Chen00c] , Mn2+ [Chen00c]

Kinetic Parameters:

Km (μM)
D-glucopyranose 6-phosphate


Chen00c: Chen L, Zhou C, Yang H, Roberts MF (2000). "Inositol-1-phosphate synthase from Archaeoglobus fulgidus is a class II aldolase." Biochemistry 39(40);12415-23. PMID: 11015222

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Mon Jul 27, 2015, biocyc14.