inositol-3-phosphate synthase (myo-inositol-1-phosphate synthase, MI-1-P synthase, MIP synthase, hIPS, myo-inositol 1-phosphate synthase A1, hINO1, INO1, ISYNA1)

Function: - key enzyme in myo-inositol biosynthesis pathway that catalyzes the conversion of glucose 6-phosphate to 1-myo-inositol 1-phosphate in a NAD-dependent manner - rate-limiting enzyme in the synthesis of all inositol- containing compounds - inhibited by mood-stabilizing drugs such as valproate & lithium - polyol metabolism; myo-inositol biosynthesis - myo-inositol from D-glucose 6-phosphate: step 1/2 D-glucose 6-phosphate 1D-myo-inositol 3-phosphate Cofactor: NAD Kinetic parameters: - KM=0.57 mM for 6-phosphate - KM=8 uM for NAD - Optimum pH is 8.0 Structure: - belongs to the myo-inositol-1-phosphate synthase family Compartment: cytoplasm (putative) Alternative splicing: named isoforms=2 Expression: - highly expressed in testis, ovary, heart, placenta & pancreas - weakly expressed in blood leukocyte, thymus, skeletal muscle & colon - induced by glucose & lovastatin - up-regulation is prevented by mevalonic acid, farnesol, & geranylgeraniol - up-regulated by E2F1

Properties

SIZE: entity length = 558 aa MW = 61 kD COMPARTMENT: cytoplasm MOTIF: active site

Database Correlations

UniProt Q9NPH2 PFAM correlations Kegg hsa:5147 ENZYME 5.5.1.4

References

UniProt :accession Q9NPH2