Phosphatidylinositol-5,4-bisphosphate, the precursor to second messengers of the phosphoinositide signal transduction pathways, is thought to be involved in the regulation of secretion, cell proliferation, differentiation, and motility. The protein encoded by this gene is one of a family of enzymes capable of catalyzing the phosphorylation of phosphatidylinositol-5-phosphate on the fourth hydroxyl of the myo-inositol ring to form phosphatidylinositol-5,4-bisphosphate. The amino acid sequence of this enzyme does not show homology to other kinases, but the recombinant protein does exhibit kinase activity. This gene is a member of the phosphatidylinositol-5-phosphate 4-kinase family. [provided by RefSeq, Jul 2008]
Function:
Catalyzes 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.
Subcellular Location:
Cell membrane By similarity. Nucleus. Cytoplasm. 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.
Tissue Specificity:
Expressed ubiquitously, with high levels in the brain. Present in most tissues, except notably skeletal muscle and small intestine.
Similarity:
Contains 1 PIPK domain.
SWISS:
P48426
Gene ID:
5305
Database links:
Entrez Gene: 420504 Chicken
Entrez Gene: 533289 Cow
Entrez Gene: 5305 Human
Entrez Gene: 18718 Mouse
Entrez Gene: 116723 Rat
Omim: 603140 Human
SwissProt: Q5F356 Chicken
SwissProt: P48426 Human
SwissProt: O70172 Mouse
SwissProt: Q9R0I8 Rat
Unigene: 57079 Human
Unigene: 313977 Mouse
Unigene: 24177 Rat
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