AKT3 (v-akt murine thymoma viral oncogene homolog 3, Protein Kinase B gamma)

2007-07-01   Mitchell Cheung , Joseph R. Testa 

Human Genetics Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA





The AKT3 gene is composed of 14 exons spanning a genomic region of 354,937 bp.


AKT3 coding sequence consists of 1,440 bp from the start codon to the stop codon.


Atlas Image
Diagram of the AKT3 protein in scale. The numbers represent specific residues. The domains are PH (Pleckstrin Homology), a short helical region, Kinase (Catalytic Kinase), and Regulatory (Regulatory Region). Indicated are the two phosphorylation sites shown to be essential for activation of AKT3: Threonine 305 and serine 472. C: Carboxyl-terminal; N: Amino-terminal.


The AKT3 serine/threonine kinase consists of 479 amino acids with a calculated molecular weight of 55.8 kDa (approximate molecular weight of 59-60 kDa seen on a Western blot). The protein contains three important regions: the PH domain at the N terminus (residues 1-107), a kinase domain (residues 148-405), and a C-terminal regulatory domain (residues 406-479). A 465-amino acid splice variant lacking the serine 472 residue has been identified, which results from alternative splicing of an exon at the C terminus.


Northern blot analysis of AKT3 indicated that it is expressed in virtually all tissues, predominantly in the brain and fetal heart and at lower levels in liver and skeletal muscle. RT-PCR analysis also indicated expression of AKT3 in a wide variety of tissues.


Predominantly cytoplasmic; also found at the plasma membrane and in the nucleus following its activation.


AKT family members are serine/threonine kinases activated following stimulation by growth factors, hormones and the extracellular matrix. AKT kinases play a key role in proliferation, cell survival, and tumorigenesis. Binding of ligands (e.g., EGF) to tyrosine kinase receptors or G-protein coupled receptors leads to the recruitment and activation of the Class 1A and Class 1B PI3K (Phosphatidylinositol 3-Kinase), respectively. The pleckstrin homology domain of AKT kinases has affinity for the 3-phosphorylated phosphoinositides 3,4,5-trisphosphate (PI-3,4,5-P3) and PI-3,4-P2 produced by PI3K, and they are activated specifically by the latter lipid. Phospholipid binding triggers the translocation of AKT kinases to the plasma membrane. There, AKT is activated through phosphorylation of a threonine (T308 in AKT1, T309 in AKT2 and T305 in AKT3) by PDK1 and on a serine (S473 on AKT1, S474 on AKT2, and S472 on AKT3) by PDK2. Activated AKT then phosphorylates a number of different substrates involved in survival, cell cycle progression, and other pathways implicated in tumorigenesis.


AKT3 is a serine/threonine kinase and is a member of the AKT family that also includes AKT1 and AKT2. At the protein level, AKT3 shows overall 83.6% identity with AKT1 and 78% identity with AKT2. The three AKT kinases are identical in the ATP binding region, except for one residue: Ala 230 of AKT1 is conserved in AKT2 (Ala 232), but switches to Val 228 in AKT3.



No germline or somatic mutations were discovered through sequencing.

Implicated in

Entity name
Breast Cancer
AKT3 was found to be expressed at a higher level in estrogen receptor-negative breast cancer compared to estrogen receptor-positive cancers, thus possibly contributing to the more aggressive phenotype of the former. AKT3 activity was also 30-to 60-fold higher in two estrogen receptor-negative cell lines as compared to two estrogen receptor-positive cell lines.
Entity name
Hepatocellular carcinoma (Hepatitis C virus related)
Using array-CGH analysis, gene copy number increases of AKT3 were found in 6 out of 19 (32%) tumors, including small, well-differentiated carcinomas. Thus, increased copies of the gene may play a potentially important role in the onset of Hepatitis C-related hepatocellular carcinoma.
Entity name
AKT3 was demonstrated to be the predominant AKT isoform involved in melanoma tumorigenesis. Knockdown of AKT3 with siRNA was shown to decrease total phospho-AKT levels in four melanoma cell lines and in normal melanocytes. In contrast, targeting the other two AKT proteins had no effect. AKT3 protein was overexpressed in 60% of primary melanoma tumors compared to normal melanocytes. Immunoprecipitation of AKT3 followed by immunoblotting with a phospho-specific AKT antibody indicated that 43% of primary melanomas have increased AKT3 activity compared to normal controls. Moreover, siRNA-mediated knockdown of AKT3 in a melanoma cell line led to a dramatic decrease in xenograft tumor size as a result of increased apoptosis.
Entity name
Ovarian Cancer
AKT3 was discovered to be highly expressed in 19 out of 92 (20%) primary ovarian tumors and also expressed in a number of ovarian tumor cell lines, including two cell lines having duplications of the AKT3 gene. The high expression of AKT3 in cell lines appeared to correlate with high total phospho-AKT levels, increased proliferation, and the ability to grow in serum starved conditions. SiRNA-mediated silencing of AKT3 expression in the OVCA429 and DOV13 cell lines resulted in reduced proliferation due to inhibition of the cell cycle.
Entity name
Prostate Cancer
AKT3 was found to be expressed at a higher level and with a 20- to 40-fold higher activity in androgen-insensitive prostate cancer compared to androgen-sensitive prostate cancer. The loss of PTEN expression appeared to contribute to increased AKT3 activity in one of the cell lines examined. Thus, AKT3 may play a role in the more aggressive phenotype of androgen-insensitive prostate cancers.


Pubmed IDLast YearTitleAuthors
162882922005Perturbations of the AKT signaling pathway in human cancer.Altomare DA et al
150343042004A portrait of AKT kinases: human cancer and animal models depict a family with strong individualities.Bellacosa A et al
113873452001Two splice variants of protein kinase B gamma have different regulatory capacity depending on the presence or absence of the regulatory phosphorylation site serine 472 in the carboxyl-terminal hydrophobic domain.Brodbeck D et al
171788672006A specific role for AKT3 in the genesis of ovarian cancer through modulation of G(2)-M phase transition.Cristiano BE et al
151334722004Analysis of DNA copy number aberrations in hepatitis C virus-associated hepatocellular carcinomas by conventional CGH and array CGH.Hashimoto K et al
104911921999Molecular cloning, expression and characterization of the human serine/threonine kinase Akt-3.Masure S et al
107736622000Mapping of AKT3, encoding a member of the Akt/protein kinase B family, to human and rodent chromosomes by fluorescence in situ hybridization.Murthy SS et al
104194561999Up-regulation of Akt3 in estrogen receptor-deficient breast cancers and androgen-independent prostate cancer lines.Nakatani K et al
154661932004Deregulated Akt3 activity promotes development of malignant melanoma.Stahl JM et al
114898292001AKT-1, -2, and -3 are expressed in both normal and tumor tissues of the lung, breast, prostate, and colon.Zinda MJ et al

Other Information

Locus ID:

NCBI: 10000
MIM: 611223
HGNC: 393
Ensembl: ENSG00000117020


dbSNP: 10000
ClinVar: 10000
TCGA: ENSG00000117020


Gene IDTranscript IDUniprot

Expression (GTEx)



PathwaySourceExternal ID
MAPK signaling pathwayKEGGko04010
ErbB signaling pathwayKEGGko04012
Autophagy - animalKEGGko04140
mTOR signaling pathwayKEGGko04150
VEGF signaling pathwayKEGGko04370
Focal adhesionKEGGko04510
Toll-like receptor signaling pathwayKEGGko04620
Jak-STAT signaling pathwayKEGGko04630
T cell receptor signaling pathwayKEGGko04660
B cell receptor signaling pathwayKEGGko04662
Fc epsilon RI signaling pathwayKEGGko04664
Insulin signaling pathwayKEGGko04910
Progesterone-mediated oocyte maturationKEGGko04914
Adipocytokine signaling pathwayKEGGko04920
Colorectal cancerKEGGko05210
Renal cell carcinomaKEGGko05211
Pancreatic cancerKEGGko05212
Endometrial cancerKEGGko05213
Prostate cancerKEGGko05215
Chronic myeloid leukemiaKEGGko05220
Acute myeloid leukemiaKEGGko05221
Small cell lung cancerKEGGko05222
Non-small cell lung cancerKEGGko05223
MAPK signaling pathwayKEGGhsa04010
ErbB signaling pathwayKEGGhsa04012
Autophagy - animalKEGGhsa04140
mTOR signaling pathwayKEGGhsa04150
VEGF signaling pathwayKEGGhsa04370
Focal adhesionKEGGhsa04510
Toll-like receptor signaling pathwayKEGGhsa04620
Jak-STAT signaling pathwayKEGGhsa04630
T cell receptor signaling pathwayKEGGhsa04660
B cell receptor signaling pathwayKEGGhsa04662
Fc epsilon RI signaling pathwayKEGGhsa04664
Insulin signaling pathwayKEGGhsa04910
Adipocytokine signaling pathwayKEGGhsa04920
Pathways in cancerKEGGhsa05200
Colorectal cancerKEGGhsa05210
Renal cell carcinomaKEGGhsa05211
Pancreatic cancerKEGGhsa05212
Endometrial cancerKEGGhsa05213
Prostate cancerKEGGhsa05215
Chronic myeloid leukemiaKEGGhsa05220
Acute myeloid leukemiaKEGGhsa05221
Small cell lung cancerKEGGhsa05222
Non-small cell lung cancerKEGGhsa05223
Chemokine signaling pathwayKEGGko04062
Chemokine signaling pathwayKEGGhsa04062
Neurotrophin signaling pathwayKEGGko04722
Neurotrophin signaling pathwayKEGGhsa04722
Fc gamma R-mediated phagocytosisKEGGko04666
Fc gamma R-mediated phagocytosisKEGGhsa04666
Progesterone-mediated oocyte maturationKEGGhsa04914
Chagas disease (American trypanosomiasis)KEGGko05142
Chagas disease (American trypanosomiasis)KEGGhsa05142
Carbohydrate digestion and absorptionKEGGko04973
Carbohydrate digestion and absorptionKEGGhsa04973
Hepatitis CKEGGko05160
Hepatitis CKEGGhsa05160
Osteoclast differentiationKEGGko04380
Osteoclast differentiationKEGGhsa04380
Influenza AKEGGko05164
Influenza AKEGGhsa05164
Cholinergic synapseKEGGhsa04725
HTLV-I infectionKEGGko05166
HTLV-I infectionKEGGhsa05166
Dopaminergic synapseKEGGko04728
Dopaminergic synapseKEGGhsa04728
Epstein-Barr virus infectionKEGGhsa05169
Epstein-Barr virus infectionKEGGko05169
PI3K-Akt signaling pathwayKEGGhsa04151
PI3K-Akt signaling pathwayKEGGko04151
Hepatitis BKEGGhsa05161
HIF-1 signaling pathwayKEGGhsa04066
Proteoglycans in cancerKEGGhsa05205
Proteoglycans in cancerKEGGko05205
Estrogen signaling pathwayKEGGhsa04915
Estrogen signaling pathwayKEGGko04915
TNF signaling pathwayKEGGhsa04668
TNF signaling pathwayKEGGko04668
Prolactin signaling pathwayKEGGhsa04917
Prolactin signaling pathwayKEGGko04917
Non-alcoholic fatty liver disease (NAFLD)KEGGhsa04932
Non-alcoholic fatty liver disease (NAFLD)KEGGko04932
Ras signaling pathwayKEGGhsa04014
Rap1 signaling pathwayKEGGhsa04015
Rap1 signaling pathwayKEGGko04015
Adrenergic signaling in cardiomyocytesKEGGhsa04261
Adrenergic signaling in cardiomyocytesKEGGko04261
FoxO signaling pathwayKEGGhsa04068
Thyroid hormone signaling pathwayKEGGhsa04919
Platelet activationKEGGhsa04611
cGMP-PKG signaling pathwayKEGGhsa04022
cGMP-PKG signaling pathwayKEGGko04022
AMPK signaling pathwayKEGGhsa04152
AMPK signaling pathwayKEGGko04152
cAMP signaling pathwayKEGGhsa04024
cAMP signaling pathwayKEGGko04024
Signaling pathways regulating pluripotency of stem cellsKEGGhsa04550
Signaling pathways regulating pluripotency of stem cellsKEGGko04550
Central carbon metabolism in cancerKEGGhsa05230
Choline metabolism in cancerKEGGhsa05231
Central carbon metabolism in cancerKEGGko05230
Choline metabolism in cancerKEGGko05231
PI3K-Akt signalingKEGGhsa_M00676
PI3K-Akt signalingKEGGM00676
Sphingolipid signaling pathwayKEGGhsa04071
Glucagon signaling pathwayKEGGhsa04922
Sphingolipid signaling pathwayKEGGko04071
Glucagon signaling pathwayKEGGko04922
Regulation of lipolysis in adipocytesKEGGhsa04923
Diseases of signal transductionREACTOMER-HSA-5663202
PI3K/AKT Signaling in CancerREACTOMER-HSA-2219528
Constitutive Signaling by AKT1 E17K in CancerREACTOMER-HSA-5674400
Immune SystemREACTOMER-HSA-168256
Adaptive Immune SystemREACTOMER-HSA-1280218
Costimulation by the CD28 familyREACTOMER-HSA-388841
CD28 co-stimulationREACTOMER-HSA-389356
CD28 dependent PI3K/Akt signalingREACTOMER-HSA-389357
CTLA4 inhibitory signalingREACTOMER-HSA-389513
Signaling by the B Cell Receptor (BCR)REACTOMER-HSA-983705
Downstream signaling events of B Cell Receptor (BCR)REACTOMER-HSA-1168372
PIP3 activates AKT signalingREACTOMER-HSA-1257604
AKT phosphorylates targets in the cytosolREACTOMER-HSA-198323
AKT phosphorylates targets in the nucleusREACTOMER-HSA-198693
Negative regulation of the PI3K/AKT networkREACTOMER-HSA-199418
Innate Immune SystemREACTOMER-HSA-168249
DAP12 interactionsREACTOMER-HSA-2172127
DAP12 signalingREACTOMER-HSA-2424491
Fc epsilon receptor (FCERI) signalingREACTOMER-HSA-2454202
Role of LAT2/NTAL/LAB on calcium mobilizationREACTOMER-HSA-2730905
Platelet activation, signaling and aggregationREACTOMER-HSA-76002
GPVI-mediated activation cascadeREACTOMER-HSA-114604
Signal TransductionREACTOMER-HSA-162582
Signaling by EGFRREACTOMER-HSA-177929
GAB1 signalosomeREACTOMER-HSA-180292
Signalling by NGFREACTOMER-HSA-166520
NGF signalling via TRKA from the plasma membraneREACTOMER-HSA-187037
PI3K/AKT activationREACTOMER-HSA-198203
Signaling by PDGFREACTOMER-HSA-186797
Downstream signal transductionREACTOMER-HSA-186763
Signaling by VEGFREACTOMER-HSA-194138
VEGFR2 mediated vascular permeabilityREACTOMER-HSA-5218920
Signaling by SCF-KITREACTOMER-HSA-1433557
Signaling by ERBB2REACTOMER-HSA-1227986
Downregulation of ERBB2:ERBB3 signalingREACTOMER-HSA-1358803
Signaling by GPCRREACTOMER-HSA-372790
GPCR downstream signalingREACTOMER-HSA-388396
G-protein beta:gamma signallingREACTOMER-HSA-397795
G beta:gamma signalling through PI3KgammaREACTOMER-HSA-392451
Gene ExpressionREACTOMER-HSA-74160
Generic Transcription PathwayREACTOMER-HSA-212436
Transcriptional Regulation by TP53REACTOMER-HSA-3700989
TP53 Regulates Metabolic GenesREACTOMER-HSA-5628897
Cell CycleREACTOMER-HSA-1640170
Cell Cycle, MitoticREACTOMER-HSA-69278
Mitotic G1-G1/S phasesREACTOMER-HSA-453279
G1/S TransitionREACTOMER-HSA-69206
Cyclin E associated events during G1/S transitionREACTOMER-HSA-69202
Vesicle-mediated transportREACTOMER-HSA-5653656
Membrane TraffickingREACTOMER-HSA-199991
Programmed Cell DeathREACTOMER-HSA-5357801
Intrinsic Pathway for ApoptosisREACTOMER-HSA-109606
Activation of BH3-only proteinsREACTOMER-HSA-114452
Activation of BAD and translocation to mitochondriaREACTOMER-HSA-111447
Developmental BiologyREACTOMER-HSA-1266738
Regulation of beta-cell developmentREACTOMER-HSA-186712
Regulation of gene expression in beta cellsREACTOMER-HSA-210745
AKT-mediated inactivation of FOXO1AREACTOMER-HSA-211163
Insulin resistanceKEGGhsa04931
Phospholipase D signaling pathwayKEGGko04072
Phospholipase D signaling pathwayKEGGhsa04072
AGE-RAGE signaling pathway in diabetic complicationsKEGGko04933
AGE-RAGE signaling pathway in diabetic complicationsKEGGhsa04933
Longevity regulating pathwayKEGGhsa04211
Longevity regulating pathway - multiple speciesKEGGko04213
Longevity regulating pathway - multiple speciesKEGGhsa04213
Regulation of TP53 ActivityREACTOMER-HSA-5633007
Regulation of TP53 Expression and DegradationREACTOMER-HSA-6806003
Regulation of TP53 DegradationREACTOMER-HSA-6804757
Regulation of TP53 Activity through Association with Co-factorsREACTOMER-HSA-6804759
Regulation of TP53 Activity through AcetylationREACTOMER-HSA-6804758
EGFR tyrosine kinase inhibitor resistanceKEGGko01521
Platinum drug resistanceKEGGko01524
Endocrine resistanceKEGGko01522
Platinum drug resistanceKEGGhsa01524
EGFR tyrosine kinase inhibitor resistanceKEGGhsa01521
Endocrine resistanceKEGGhsa01522
Breast cancerKEGGko05224
Breast cancerKEGGhsa05224
Downregulation of ERBB2 signalingREACTOMER-HSA-8863795
RAB GEFs exchange GTP for GDP on RABsREACTOMER-HSA-8876198
Fluid shear stress and atherosclerosisKEGGko05418
Fluid shear stress and atherosclerosisKEGGhsa05418
Apelin signaling pathwayKEGGhsa04371

Protein levels (Protein atlas)

Not detected


Entity IDNameTypeEvidenceAssociationPKPDPMIDs


Pubmed IDYearTitleCitations
227292242012De novo germline and postzygotic mutations in AKT3, PIK3R2 and PIK3CA cause a spectrum of related megalencephaly syndromes.203
154661932004Deregulated Akt3 activity promotes development of malignant melanoma.200
227292232012De novo somatic mutations in components of the PI3K-AKT3-mTOR pathway cause hemimegalencephaly.193
225006282012Somatic activation of AKT3 causes hemispheric developmental brain malformations.147
188133152008A novel AKT3 mutation in melanoma tumours and cell lines.103
206473172010Akt3-mediated resistance to apoptosis in B-RAF-targeted melanoma cells.95
199131212009Gene-centric association signals for lipids and apolipoproteins identified via the HumanCVD BeadChip.85
222624092012In hepatocellular carcinoma miR-519d is up-regulated by p53 and DNA hypomethylation and targets CDKN1A/p21, PTEN, AKT3 and TIMP2.78
184511712008Akt3 and mutant V600E B-Raf cooperate to promote early melanoma development.75
257222882015PI3K/AKT pathway mutations cause a spectrum of brain malformations from megalencephaly to focal cortical dysplasia.73


Mitchell Cheung ; Joseph R. Testa

AKT3 (v-akt murine thymoma viral oncogene homolog 3, Protein Kinase B gamma)

Atlas Genet Cytogenet Oncol Haematol. 2007-07-01

Online version: http://atlasgeneticsoncology.org/gene/615/akt3