LMPD Database

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LMP005569

UniProt Annotations

Entry Information
Gene Nameinositol-tetrakisphosphate 1-kinase
Protein EntryITPK1_HUMAN
UniProt IDQ13572
SpeciesHuman
Comments
Comment typeDescription
Alternative ProductsEvent=Alternative splicing; Named isoforms=2; Name=1; IsoId=Q13572-1; Sequence=Displayed; Name=2; IsoId=Q13572-2; Sequence=VSP_016478, VSP_016479; Note=No experimental confirmation available.;
Biophysicochemical PropertiesKinetic parameters: KM=0.3 uM for Ins(1,3,4)P3 ; KM=0.1 uM for Ins(3,4,5,6)P4 ; Vmax=320 pmol/min/ug enzyme with Ins(1,3,4)P3 as substrate ; Vmax=780 pmol/min/ug enzyme enzyme with Ins(3,4,5,6)P4 as substrate ;
Catalytic ActivityATP + 1D-myo-inositol 1,3,4-trisphosphate = ADP + 1D-myo-inositol 1,3,4,5-tetrakisphosphate.
Catalytic ActivityATP + 1D-myo-inositol 1,3,4-trisphosphate = ADP + 1D-myo-inositol 1,3,4,6-tetrakisphosphate.
Catalytic ActivityATP + 1D-myo-inositol 3,4,5,6- tetrakisphosphate = ADP + 1D-myo-inositol 1,3,4,5,6- pentakisphosphate.
CautionPubMed:11533064 detected some protein kinase activity and ability to phosphorylate transcription factors c-jun/JUN and ATF2. However, PubMed:15762844 showed that it does not have protein kinase activity.
CofactorName=Mg(2+); Xref=ChEBI
FunctionKinase that can phosphorylate various inositol polyphosphate such as Ins(3,4,5,6)P4 or Ins(1,3,4)P3. Phosphorylates Ins(3,4,5,6)P4 at position 1 to form Ins(1,3,4,5,6)P5. This reaction is thought to have regulatory importance, since Ins(3,4,5,6)P4 is an inhibitor of plasma membrane Ca(2+)-activated Cl(-) channels, while Ins(1,3,4,5,6)P5 is not. Also phosphorylates Ins(1,3,4)P3 on O-5 and O-6 to form Ins(1,3,4,6)P4, an essential molecule in the hexakisphosphate (InsP6) pathway. Also acts as an inositol polyphosphate phosphatase that dephosphorylate Ins(1,3,4,5)P4 and Ins(1,3,4,6)P4 to Ins(1,3,4)P3, and Ins(1,3,4,5,6)P5 to Ins(3,4,5,6)P4. May also act as an isomerase that interconverts the inositol tetrakisphosphate isomers Ins(1,3,4,5)P4 and Ins(1,3,4,6)P4 in the presence of ADP and magnesium. Probably acts as the rate-limiting enzyme of the InsP6 pathway. Modifies TNF-alpha-induced apoptosis by interfering with the activation of TNFRSF1A-associated death domain. {ECO
PtmAcetylation by EP300 and CREBBP destabilizes ITPK1, and down- regulates enzymatic activity. Deacetylated by SIRT1.
SimilarityBelongs to the ITPK1 family.
SimilarityContains 1 ATP-grasp domain. {ECO
SubunitMonomer. Interacts with GPS1/COPS1.
Tissue SpecificityExpressed in brain > heart > skeletal muscle = kidney = pancreas = liver = placenta > lung. In brain, it is expressed in cerebellum, cerebral cortex, medulla, spinal cord, occipital lobe, frontal lobe, temporal lobe and putamen.