Inositol-trisphosphate 3-kinase B is an enzyme that in humans is encoded by the ITPKB gene. [5] [6]
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)P4, which does not gate the inositol trisphosphate receptor. The enzyme specifically phosphorylates the 1,4,5 isomer of IP3. 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. [7] Itpkb regulates immune cell function and is required for T and B cell development. [8]
Inositol trisphosphate or inositol 1,4,5-trisphosphate abbreviated InsP3 or Ins3P or IP3 is an inositol phosphate signaling molecule. It is made by hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), a phospholipid that is located in the plasma membrane, by phospholipase C (PLC). Together with diacylglycerol (DAG), IP3 is a second messenger molecule used in signal transduction in biological cells. While DAG stays inside the membrane, IP3 is soluble and diffuses through the cell, where it binds to its receptor, which is a calcium channel located in the endoplasmic reticulum. When IP3 binds its receptor, calcium is released into the cytosol, thereby activating various calcium regulated intracellular signals.
Gq protein alpha subunit is a family of heterotrimeric G protein alpha subunits. This family is also commonly called the Gq/11 (Gq/G11) family or Gq/11/14/15 family to include closely related family members. G alpha subunits may be referred to as Gq alpha, Gαq, or Gqα. Gq proteins couple to G protein-coupled receptors to activate beta-type phospholipase C (PLC-β) enzymes. PLC-β in turn hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) to diacyl glycerol (DAG) and inositol trisphosphate (IP3). IP3 acts as a second messenger to release stored calcium into the cytoplasm, while DAG acts as a second messenger that activates protein kinase C (PKC).
Inositol 1,4,5-trisphosphate receptor type 1 is a protein that in humans is encoded by the ITPR1 gene.
SH2-domain containing Phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 2 is an enzyme that in humans is encoded by the INPPL1 gene.
Inositol (1,4,5) trisphosphate 3-kinase (EC 2.7.1.127), abbreviated here as ITP3K, is an enzyme that facilitates a phospho-group transfer from adenosine triphosphate to 1D-myo-inositol 1,4,5-trisphosphate. This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing groups (phosphotransferases) with an alcohol group as acceptor. The systematic name of this enzyme class is ATP:1D-myo-inositol-1,4,5-trisphosphate 3-phosphotransferase. ITP3K catalyzes the transfer of the gamma-phosphate from ATP to the 3-position of inositol 1,4,5-trisphosphate to form inositol 1,3,4,5-tetrakisphosphate. ITP3K is highly specific for the 1,4,5-isomer of IP3, and it exclusively phosphorylates the 3-OH position, producing Ins(1,3,4,5)P4, also known as inositol tetrakisphosphate or IP4.
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase gamma-2 is an enzyme that in humans is encoded by the PLCG2 gene.
1-Phosphatidylinositol-4,5-bisphosphate phospholipase beta-1 is an enzyme that in humans is encoded by the PLCB1 gene.
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase beta-2 is an enzyme that in humans is encoded by the PLCB2 gene.
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase beta-3 is an enzyme that in humans is encoded by the PLCB3 gene.
Phospholipase C epsilon 1 (PLCE1) is an enzyme that in humans is encoded by the PLCE1 gene. This gene encodes a phospholipase enzyme (PLCE1) that catalyzes the hydrolysis of phosphatidylinositol-4,5-bisphosphate to generate two second messengers: inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG). Mutations in this gene cause early-onset nephrotic syndrome and have been associated with respiratory chain deficiency with diffuse mesangial sclerosis.
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase delta-3 is an enzyme that in humans is encoded by the PLCD3 gene.
Inositol-trisphosphate 3-kinase A is an enzyme that in humans is encoded by the ITPKA gene.
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase beta-4 is an enzyme that in humans is encoded by the PLCB4 gene.
Putative adenosylhomocysteinase 2 is an enzyme that in humans is encoded by the AHCYL1 gene.
Ras GTPase-activating protein 3 is an enzyme that in humans is encoded by the RASA3 gene.
Protein MRVI1 is a protein that in humans is encoded by the MRVI1 gene.
cGMP-dependent protein kinase 1, alpha isozyme is an enzyme that in humans is encoded by the PRKG1 gene.
Inositol 1,4,5-trisphosphate receptor, type 2, also known as ITPR2, is a protein which in humans is encoded by the ITPR2 gene. The protein encoded by this gene is both a receptor for inositol triphosphate and a calcium channel.
Inositol 1,4,5-trisphosphate receptor, type 3, also known as ITPR3, is a protein which in humans is encoded by the ITPR3 gene. The protein encoded by this gene is both a receptor for inositol triphosphate and a calcium channel.
Inositol-polyphosphate multikinase is an enzyme with systematic name ATP:1D-myo-inositol-1,4,5-trisphosphate 6-phosphotransferase. This enzyme catalyses the following chemical reaction