inositol hexakisphosphate & diphosphoinositol-pentakisphosphate kinase 2 (insP6 & PP-IP5 kinase 2, PP-IP5 kinase 2, hsVIP2, histidine acid phosphatase domain-containing protein 1, HISPPD1, KIAA0433, PPIP5K2, VIP2)

Function: - bifunctional inositol kinase - catalyzes formation of diphosphoinositol pentakisphosphate (insP7 or PP-insP5) & bi-diphosphoinositol tetrakisphosphate (insP8 or PP2-insP4) converts inositolitol hexakisphosphate (insP6) to insP7 - also able to convert insP7 to insP8 - probably specifically mediates formation of 4PP-insP5 & 6PP-insP5 insP7 isomers but not of 5PP-IP5 insP7 isomer ATP + 1D-myo-inositol hexakisphosphate ADP + 5-diphospho-1D-myo-inositol (1,2,3,4,6)pentakisphosphate ATP + 1D-myo-inositol 1,3,4,5,6-pentakisphosphate ADP + diphospho-1D-myo-inositol tetrakisphosphate (isomeric configuration unknown) ATP + 1D-myo-inositol 5-diphosphate pentakisphosphate ADP + 1D-myo-inositol bisdiphosphate tetrakisphosphate (isomeric configuration unknown) Kinetic parameters: - KM=0.13 uM for insP6 - KM=0.19 uM for insP7 - Vmax=0.39 nmol/min/mg enzyme with insP6 as substrate - Vmax=1.38 nmol/min/mg enzyme with insP7 as substrate Structure: - belongs to the histidine acid phosphatase family. VIP1 subfamily - although related to histidine acid phosphatases, it lacks the conserved active sites, suggesting that it has no phosphatase activity Compartment: cytoplasm, cytosol Alternative splicing: named isoforms=2

General

kinase or ATP-phosphotransferase phosphoprotein

Properties

SIZE: entity length = 1243 aa MW = 140 kD COMPARTMENT: cytoplasm MOTIF: Ser phosphorylation site {S38} Ser phosphorylation site {S504} Thr phosphorylation site {T1185}

Database Correlations

UniProt O43314 Pfam PF00328 ENZYME correlations

References

UniProt :accession O43314