Background
Human AKT serine-threonine protein kinase family includes three members AKT1,AKT2,
AKT3, which are also often referred to as protein kinase B alpha, beta, and gamma. These
highly similar AKT proteins all have an N-terminal pleckstrin homology domain, a
serine/threonine-specific kinase domain and a C-terminal regulatory domain. These proteins
are phosphorylated by phosphoinositide 3-kinase (PI3K). AKT/PI3K forms a key component of
many signalling pathways that involve the binding of membrane-bound ligands such as
receptor tyrosine kinases, G-protein coupled receptors, and integrin-linked kinase. These
AKT proteins therefore regulate a wide variety of cellular functions including cell
proliferation, survival, metabolism, and angiogenesis in both normal and malignant cells.
AKT proteins are recruited to the cell membrane by phosphatidylinositol 3,4,5-trisphosphate
(PIP3) after phosphorylation of phosphatidylinositol 4,5-bisphosphate (PIP2) by PI3K.
Subsequent phosphorylation of both threonine residue 308 and serine residue 473 is
required for full activation of the AKT1 protein encoded by this gene.
