"Stock A Strain k AKR mouse originally inbred in the laboratory of Dr. C. P. Rhoads by K. B. Rhoads at the Rockefeller Institute." When the oncogene encoded in this virus was discovered, it was termed v-Akt. Thus, the more recently identified human analogs were named accordingly. Regulation Akt1 is involved in the PI3K/AKT/mTOR pathway and other signaling pathways. Binding phospholipids The Akt proteins possess a protein domain known as a PH domain, or pleckstrin homology domain, named after pleckstrin, the protein in which it was first discovered. This domain binds to phosphoinositides with high affinity. In the case of the PH domain of the Akt proteins, it binds either PIP3 (phosphatidylinositol (3,4,5)-trisphosphate, PtdIns(3,4,5)P3) or PIP2 (phosphatidylinositol (3,4)-bisphosphate, PtdIns(3,4)P2). This is useful for control of cellular signaling because the di-phosphorylated phosphoinositide PIP2 is only phosphorylated by the family of enzymes, PI 3-kinases (phosphoinositide 3-kinase or PI3-K), and only upon receipt of chemical messengers which tell the cell to begin the growth process. For example, PI 3-kinases may be activated by a G protein coupled receptor or receptor tyrosine kinase such as the insulin receptor. Once activated, PI 3-kinase phosphorylates PIP2 to form PIP3. Phosphorylation Once correctly positioned at the membrane via binding of PIP3, Akt can then be phosphorylated by its activating kinases, phosphoinositide dependent kinase 1 (PDPK1 at threonine 308 in Akt1 and threonine 309 in Akt2) and the mammalian target of rapamycin complex 2 (mTORC2 at serine 473 (Akt1) and 474 (Akt2)) which is found at high levels in the fed state, first by mTORC2. mTORC2 therefore functionally acts as the long-sought PDK2 molecule, although other molecules, including integrin-linked kinase (ILK) and mitogen-activated protein kinase-activated protein kinase-2 (MAPKAPK2) can also serve as PDK2. Phosphorylation by mTORC2 stimulates the subsequent phosphorylation of Akt isoforms by PDPK1. Activated Akt isoforms can then go on to activate or deactivate their myriad substrates (e.g. mTOR) via their kinase activity. Besides being a downstream effector of PI 3-kinases, Akt isoforms can also be activated in a PI 3-kinase-independent manner. ACK1 or TNK2, a non-receptor tyrosine kinase, phosphorylates Akt at its tyrosine 176 residue, leading to its activation in PI 3-kinase-independent manner. Studies have suggested that cAMP-elevating agents could also activate Akt through protein kinase A (PKA) in the presence of insulin. O-GlcNAcylation Akt can be O-GlcNAcylated by OGT. O-GlcNAcylation of Akt is associated with a decrease in T308 phosphorylation. Ubiquitination Akt1 is normally