Phosphatidylinositol 3-kinase-related kinases (PIKKs) are a family of Ser/Thr-protein kinases with sequence similarity to phosphatidylinositol-3 kinases (PI3Ks). [1]
The human PIKK family includes six members:
Gene | Protein | Function |
---|---|---|
ATM | ataxia-telangiectasia mutated | response to DNA damage |
ATR | ataxia- and Rad3-related | " |
PRKDC | DNA-dependent protein kinase catalytic subunit (DNA-PKcs) | " |
MTOR | mammalian target of rapamycin (mTOR) | nutrient-regulated kinase that controls metabolism and cell growth |
SMG1 | suppressor of morphogenesis in genitalia | regulates nonsense-mediated mRNA decay |
TRRAP | transformation/transcription domain-associated protein | transcription factor co-activator |
PIKKs proteins contain the following four domains:
ATM serine/threonine kinase, symbol ATM, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks. It phosphorylates several key proteins that initiate activation of the DNA damage checkpoint, leading to cell cycle arrest, DNA repair or apoptosis. Several of these targets, including p53, CHK2, BRCA1, NBS1 and H2AX are tumor suppressors.
Phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3), abbreviated PIP3, is the product of the class I phosphoinositide 3-kinases (PI 3-kinases) phosphorylation of phosphatidylinositol (4,5)-bisphosphate (PIP2). It is a phospholipid that resides on the plasma membrane.
Phosphoinositide 3-kinases (PI3Ks), also called phosphatidylinositol 3-kinases, are a family of enzymes involved in cellular functions such as cell growth, proliferation, differentiation, motility, survival and intracellular trafficking, which in turn are involved in cancer.
Class III PI 3-kinase is a subgroup of the enzyme family, phosphoinositide 3-kinase that share a common protein domain structure, substrate specificity and method of activation.
Phosphatidylinositol 4,5-bisphosphate or PtdIns(4,5)P2, also known simply as PIP2 or PI(4,5)P2, is a minor phospholipid component of cell membranes. PtdIns(4,5)P2 is enriched at the plasma membrane where it is a substrate for a number of important signaling proteins.
Phosphatidylinositol 3-phosphate (PtdIns3P) is a phospholipid found in cell membranes that helps to recruit a range of proteins, many of which are involved in protein trafficking, to the membranes. It is the product of both the class II and III phosphoinositide 3-kinases activity on phosphatidylinositol.
Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta isoform also known as phosphoinositide 3-kinase (PI3K) delta isoform or p110δ is an enzyme that in humans is encoded by the PIK3CD gene.
GRB2-associated-binding protein 2 also known as GAB2 is a protein that in humans is encoded by the GAB2 gene.
Phosphatidylinositol transfer protein (PITP) or priming in exocytosis protein 3 (PEP3) is a ubiquitous cytosolic domain involved in transport of phospholipids from their site of synthesis in the endoplasmic reticulum and Golgi to other cell membranes.
Src homology 2 (SH2) domain containing inositol polyphosphate 5-phosphatase 1(SHIP1) is an enzyme with phosphatase activity. SHIP1 is structured by multiple domain and is encoded by the INPP5D gene in humans. SHIP1 is expressed predominantly by hematopoietic cells but also, for example, by osteoblasts and endothelial cells. This phosphatase is important for the regulation of cellular activation. Not only catalytic but also adaptor activities of this protein are involved in this process. Its movement from the cytosol to the cytoplasmic membrane, where predominantly performs its function, is mediated by tyrosine phosphorylation of the intracellular chains of cell surface receptors that SHIP1 binds. Insufficient regulation of SHIP1 leads to different pathologies.
Phosphatidylinositol-4-phosphate 3-kinase C2 domain-containing beta polypeptide is an enzyme that in humans is encoded by the PIK3C2B gene.
Phosphatidylinositol 4-kinase beta is an enzyme that in humans is encoded by the PI4KB gene.
Phosphatidylinositol 4-kinase alpha is an enzyme that in humans is encoded by the PI4KA gene.
Arf-GAP with GTPase, ANK repeat and PH domain-containing protein 2 is a protein that in humans is encoded by the AGAP2 gene.
Phosphatidylinositol-4-phosphate 3-kinase C2 domain-containing gamma polypeptide is an enzyme that in humans is encoded by the PIK3C2G gene.
Phosphatidylinositol 4-kinase 2-alpha is an enzyme that in humans is encoded by the PI4K2A gene.
In the field of biochemistry, PDPK1 refers to the protein 3-phosphoinositide-dependent protein kinase-1, an enzyme which is encoded by the PDPK1 gene in humans. It is implicated in the development and progression of melanomas.
Sorting nexins are a large group of proteins that are localized in the cytoplasm and have the potential for membrane association either through their lipid-binding PX domain or through protein–protein interactions with membrane-associated protein complexes Some members of this family have been shown to facilitate protein sorting.
mTOR inhibitors are a class of drugs that inhibit the mammalian target of rapamycin (mTOR), which is a serine/threonine-specific protein kinase that belongs to the family of phosphatidylinositol-3 kinase (PI3K) related kinases (PIKKs). mTOR regulates cellular metabolism, growth, and proliferation by forming and signaling through two protein complexes, mTORC1 and mTORC2. The most established mTOR inhibitors are so-called rapalogs, which have shown tumor responses in clinical trials against various tumor types.
Leonard (Len) R Stephens FRS is a molecular biologist, senior group leader and associate director at the Babraham Institute.
This protein-related article is a stub. You can help Wikipedia by expanding it. |