MGP Database

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MGP002299

UniProt Annotations

Entry Information
Gene Namephosphatidylinositol-5-phosphate 4-kinase, type II, alpha
Protein EntryPI42A_HUMAN
UniProt IDP48426
SpeciesHuman
Comments
Comment typeDescription
Alternative ProductsEvent=Alternative splicing; Named isoforms=2; Name=1; IsoId=P48426-1; Sequence=Displayed; Name=2; IsoId=P48426-2; Sequence=VSP_056458; Note=No experimental confirmation available.;
Biophysicochemical PropertiesKinetic parameters: KM=50 uM for phosphatidylinositol-5- phosphate {ECO:0000269|PubMed:20583997}; Vmax=466 pmol/min/ug enzyme {ECO:0000269|PubMed:20583997};
Catalytic ActivityATP + 1-phosphatidyl-1D-myo-inositol 5- phosphate = ADP + 1-phosphatidyl-1D-myo-inositol 4,5-bisphosphate. {ECO:0000269|PubMed:9367159}.
CautionThis protein was previously thought to be a phosphatidylinositol 4-phosphate 5-kinase. {ECO:0000305}.
FunctionCatalyzes the phosphorylation of phosphatidylinositol 5- phosphate (PtdIns5P) on the fourth hydroxyl of the myo-inositol ring, to form phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). May exert its function by regulating the levels of PtdIns5P, which functions in the cytosol by increasing AKT activity and in the nucleus signals through ING2. May regulate the pool of cytosolic PtdIns5P in response to the activation of tyrosine phosphorylation. May negatively regulate insulin- stimulated glucose uptake by lowering the levels of PtdIns5P. May be involved in thrombopoiesis, and the terminal maturation of megakaryocytes and regulation of their size. {ECO:0000269|PubMed:18364242}.
SimilarityContains 1 PIPK domain. {ECO:0000255|PROSITE- ProRule:PRU00781}.
Subcellular LocationCell membrane {ECO:0000250}. Nucleus {ECO:0000269|PubMed:20583997}. Cytoplasm {ECO:0000269|PubMed:20583997}. Note=May translocate from the cytosol to the cell membrane upon activation of tyrosine phosphorylation. May translocate from the inner to the outer segments of the rod photoreceptor cells in response to light (By similarity). Localization to the nucleus is modulated by the interaction with PIP4K2B. {ECO:0000250}.
SubunitHomodimer (By similarity). Interacts with PIP4K2B. Interaction with PIP4K2B may regulate localization to the nucleus. {ECO:0000250, ECO:0000269|PubMed:20583997}.
Tissue SpecificityExpressed ubiquitously, with high levels in the brain. Present in most tissues, except notably skeletal muscle and small intestine. {ECO:0000269|PubMed:7639683, ECO:0000269|PubMed:7852364}.
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