The Akt signaling pathway or PI3K-Akt signaling pathway is a signal transduction pathway that promotes survival and growth in response to extracellular signals. Key proteins involved are PI3K (phosphatidylinositol 3-kinase) and Akt (protein kinase B). Protein kinase B (PKB), also known as Akt, is the collective name of a set of three serine/threonine-specific protein kinases that play key roles in multiple cellular processes such as glucose metabolism, apoptosis, cell proliferation, transcription, and cell migration. See also Signal transduction.

Activation Akt/PKB via Receptor tyrosine kinases/Ras

Receptor tyrosine kinases

Growth factor receptor-bound proteins

Ras activation

GTPase KRas

Allosteric modulation of H-Ras GTPase

Phosphoinositide 3-Kinases

Phosphoinositide 3-Kinases or phosphatidylinositol 3-kinase (PI3K) are a family of ubiquitously distributed lipid kinases, that play a critical role in the regulation of numerous cellular processes including cellular growth and morphology, programmed cell death, cell motility and adhesion, mitogenesis and glucose uptake.

• The Structure of PI3K
• Phosphoinositide 3-Kinases
• PI3K Activation, Inhibition, & Medical Implications

PI3K can also be activated by G protein-coupled receptors (GPCRs), via G-protein βγ dimers or Ras which bind PI3K directly. In addition, the Gα subunit activates Src-dependent integrin signaling which can activate PI3K.

Phosphoinositide formation

The triphosphate form (PI(3,4,5)P3) binds Akt and phosphoinositide-dependent kinase 1 (PDK1) so they accumulate in close proximity at the membrane.

Akt/PKB

AKT1

RAC(Rho family)-alpha serine/threonine-protein kinase is an enzyme that in humans is encoded by the AKT1 gene. This enzyme belongs to the AKT subfamily of serine/threonine kinases that contain SH2 (Src homology 2-like) protein domains. See 3mv5.

AKT2

AKT2, also known as RAC-beta serine/threonine-protein kinase, is an enzyme that in humans is encoded by the AKT2 gene. It influences metabolite storage as part of the insulin signal transduction pathway. See 3d0e.