LMP005569 UniProt Annotations
Gene Name inositol-tetrakisphosphate 1-kinase
Protein Entry ITPK1_HUMAN
UniProt ID Q13572
Species Human
Comment type Description
Alternative Products Event=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 Properties Kinetic 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 Activity ATP + 1D-myo-inositol 1,3,4-trisphosphate = ADP + 1D-myo-inositol 1,3,4,5-tetrakisphosphate.
Catalytic Activity ATP + 1D-myo-inositol 1,3,4-trisphosphate = ADP + 1D-myo-inositol 1,3,4,6-tetrakisphosphate.
Catalytic Activity ATP + 1D-myo-inositol 3,4,5,6- tetrakisphosphate = ADP + 1D-myo-inositol 1,3,4,5,6- pentakisphosphate.
Caution PubMed: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.
Cofactor Name=Mg(2+); Xref=ChEBI
Function Kinase 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
Ptm Acetylation by EP300 and CREBBP destabilizes ITPK1, and down- regulates enzymatic activity. Deacetylated by SIRT1.
Similarity Belongs to the ITPK1 family.
Similarity Contains 1 ATP-grasp domain. {ECO
Subunit Monomer. Interacts with GPS1/COPS1.
Tissue Specificity Expressed 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.
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