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MGP003978

UniProt Annotations

Entry Information
Gene Namediphosphoinositol pentakisphosphate kinase 1
Protein EntryVIP1_HUMAN
UniProt IDQ6PFW1
SpeciesHuman
Comments
Comment typeDescription
Alternative ProductsEvent=Alternative splicing; Named isoforms=7; Name=1; IsoId=Q6PFW1-1; Sequence=Displayed; Name=2; IsoId=Q6PFW1-2; Sequence=VSP_030618, VSP_030622; Name=3; IsoId=Q6PFW1-3; Sequence=VSP_030618, VSP_030621; Name=4; IsoId=Q6PFW1-4; Sequence=VSP_030615, VSP_030618, VSP_030621; Name=5; IsoId=Q6PFW1-5; Sequence=VSP_030616, VSP_030619, VSP_030623; Name=6; IsoId=Q6PFW1-6; Sequence=VSP_030617; Note=No experimental confirmation available.; Name=7; IsoId=Q6PFW1-7; Sequence=VSP_030618, VSP_030620, VSP_030624; Note=No experimental confirmation available.;
Biophysicochemical PropertiesKinetic parameters: KM=0.12 uM for InsP6 {ECO:0000269|PubMed:17690096, ECO:0000269|PubMed:17702752, ECO:0000269|PubMed:21222653}; KM=0.10 uM for InsP7 {ECO:0000269|PubMed:17690096, ECO:0000269|PubMed:17702752, ECO:0000269|PubMed:21222653}; Vmax=0.03 nmol/min/mg enzyme with InsP6 as substrate {ECO:0000269|PubMed:17690096, ECO:0000269|PubMed:17702752, ECO:0000269|PubMed:21222653}; Vmax=0.13 nmol/min/mg enzyme with InsP7 as substrate {ECO:0000269|PubMed:17690096, ECO:0000269|PubMed:17702752, ECO:0000269|PubMed:21222653}; Note=The catalytic efficiency is 80 folds higher for 5-PP-InsP5 (InsP7) compared to InsP6.;
Catalytic ActivityATP + 1D-myo-inositol 1-diphosphate 2,3,4,5,6- pentakisphosphate = ADP + 1D-myo-inositol 1,5-bis(diphosphate) 2,3,4,6-tetrakisphosphate.
Catalytic ActivityATP + 1D-myo-inositol 5-diphosphate 1,2,3,4,6- pentakisphosphate = ADP + 1D-myo-inositol 1,5-bis(diphosphate) 2,3,4,6-tetrakisphosphate.
Catalytic ActivityATP + 1D-myo-inositol hexakisphosphate = ADP + 1D-myo-inositol 1-diphosphate 2,3,4,5,6-pentakisphosphate.
Catalytic ActivityATP + 1D-myo-inositol hexakisphosphate = ADP + 1D-myo-inositol 5-diphosphate 1,2,3,4,6-pentakisphosphate.
DomainThe polyphosphoinositide-binding domain mediates binding of PtdIns(3,4,5)P3 and InsP6. Despite its similarity with the phosphatase domain of histidine acid phosphatases, it has no phosphatase activity (PubMed:21222653). {ECO:0000269|PubMed:21222653}.
FunctionBifunctional inositol kinase that acts in concert with the IP6K kinases IP6K1, IP6K2 and IP6K3 to synthesize the diphosphate group-containing inositol pyrophosphates diphosphoinositol pentakisphosphate, PP-InsP5, and bis- diphosphoinositol tetrakisphosphate, (PP)2-InsP4. PP-InsP5 and (PP)2-InsP4, also respectively called InsP7 and InsP8, regulate a variety of cellular processes, including apoptosis, vesicle trafficking, cytoskeletal dynamics, exocytosis, insulin signaling and neutrophil activation. Phosphorylates inositol hexakisphosphate (InsP6) at positions 1 or 3 to produce PP-InsP5 which is in turn phosphorylated by IP6Ks to produce (PP)2-InsP4. Alternatively, phosphorylates at position 1 or 3 PP-InsP5, produced by IP6Ks from InsP6, to produce (PP)2-InsP4. Activated when cells are exposed to hyperosmotic stress. {ECO:0000269|PubMed:17412958, ECO:0000269|PubMed:17690096, ECO:0000269|PubMed:17702752}.
Sequence CautionSequence=BAA20831.2; Type=Erroneous initiation; Note=Translation N-terminally shortened.; Evidence={ECO:0000305};
SimilarityBelongs to the histidine acid phosphatase family. VIP1 subfamily. {ECO:0000305}.
Subcellular LocationCytoplasm, cytosol. Cell membrane. Note=Relocalizes to the plasma membrane upon activation of the PtdIns 3-kinase pathway.
Tissue SpecificityWidely expressed, with a higher expression in skeletal muscle, heart and brain. {ECO:0000269|PubMed:17690096}.
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