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Biochem Soc Trans. 2019 Jun 28;47(3):897-908. doi: 10.1042/BST20190013. Epub 2019 May 30.

Lipid-dependent Akt-ivity: where, when, and how.

Author information

1
Department of Structural and Computational Biology, Max F. Perutz Laboratories (MFPL), Campus Vienna Biocenter 5, 1030 Vienna, Austria.
2
Department of Medical Biochemistry, Medical University of Vienna, 1090 Vienna, Austria.
3
Department of Structural and Computational Biology, Max F. Perutz Laboratories (MFPL), Campus Vienna Biocenter 5, 1030 Vienna, Austria thomas.leonard@meduniwien.ac.at.

Abstract

Akt is an essential protein kinase activated downstream of phosphoinositide 3-kinase and frequently hyperactivated in cancer. Canonically, Akt is activated by phosphoinositide-dependent kinase 1 and mechanistic target of rapamycin complex 2, which phosphorylate it on two regulatory residues in its kinase domain upon targeting of Akt to the plasma membrane by PI(3,4,5)P3 Recent evidence, however, has shown that, in addition to phosphorylation, Akt activity is allosterically coupled to the engagement of PI(3,4,5)P3 or PI(3,4)P2 in cellular membranes. Furthermore, the active membrane-bound conformation of Akt is protected from dephosphorylation, and Akt inactivation by phosphatases is rate-limited by its dissociation. Thus, Akt activity is restricted to membranes containing either PI(3,4,5)P3 or PI(3,4)P2 While PI(3,4,5)P3 has long been associated with signaling at the plasma membrane, PI(3,4)P2 is gaining increasing traction as a signaling lipid and has been implicated in controlling Akt activity throughout the endomembrane system. This has clear implications for the phosphorylation of both freely diffusible substrates and those localized to discrete subcellular compartments.

KEYWORDS:

4; 4)P2; 5)P3; Akt; PI(3; kinase; lipids; phosphorylation/dephosphorylation

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