| The protein encoded by this gene regulates [[inositol phosphate]] metabolism by [[phosphorylation]] of second messenger [[inositol 1,4,5-trisphosphate]] to Ins(1,3,4,5)P4. The activity of this encoded protein is responsible for regulating the levels of a large number of inositol polyphosphates that are important in cellular signaling. Both calcium/calmodulin and protein phosphorylation mechanisms control its activity.<ref>{{cite web | title = Entrez Gene: ITPKB inositol 1,4,5-trisphosphate 3-kinase B| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3707| accessdate = }}</ref> Itpkb regulates immune cell function and is required for T and B cell development.<ref>{{cite journal | pmid = 20336153 | doi=10.1038/nri2745 | volume=10 | issue=4 | title=Regulation of immune cell development through soluble inositol-1,3,4,5-tetrakisphosphate | pmc=2922113 |date=April 2010 | journal=Nat. Rev. Immunol. | pages=257–71 |vauthors=Sauer K, Cooke MP }}</ref> | | The protein encoded by the ITPKB gene is one of 3 isoforms of [[Inositol-trisphosphate 3-kinase]] expressed in humans. ITPKB protein regulates [[inositol phosphate]] metabolism by [[phosphorylation]] of second messenger [[inositol 1,4,5-trisphosphate]], which releases calcium from intracellular store in the [[endoplasmic reticulum]] by gating the [[inositol trisphosphate receptor]]. ITPKB produces Ins(1,3,4,5)P<small>4</small>, which does ''not'' gate the [[inositol trisphosphate receptor]]. The enzyme specifically phosphorylates the 1,4,5 isomer of [[inositol 1,4,5-trisphosphate|IP<small>3</small>]]. The activity of this encoded protein is responsible for regulating the levels of a large number of inositol polyphosphates that are important in cellular signaling. Both calcium/calmodulin and protein phosphorylation mechanisms control its activity.<ref>{{cite web | title = Entrez Gene: ITPKB inositol 1,4,5-trisphosphate 3-kinase B| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3707| accessdate = }}</ref> Itpkb regulates immune cell function and is required for T and B cell development.<ref>{{cite journal | pmid = 20336153 | doi=10.1038/nri2745 | volume=10 | issue=4 | title=Regulation of immune cell development through soluble inositol-1,3,4,5-tetrakisphosphate | pmc=2922113 |date=April 2010 | journal=Nat. Rev. Immunol. | pages=257–71 |vauthors=Sauer K, Cooke MP }}</ref> |
