scholarly journals DNA-dependent Protein Kinase-mediated Phosphorylation of Protein Kinase B Requires a Specific Recognition Sequence in the C-terminal Hydrophobic Motif

2009 ◽  
Vol 284 (10) ◽  
pp. 6169-6174 ◽  
Author(s):  
Jongsun Park ◽  
Jianhua Feng ◽  
Yuwen Li ◽  
Ola Hammarsten ◽  
Derek P. Brazil ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase B ◽  
Recognition Sequence ◽  
Dependent Protein Kinase ◽  
Specific Recognition ◽  
Dependent Protein ◽  
Hydrophobic Motif

scholarly journals Domain Swapping Used To Investigate the Mechanism of Protein Kinase B Regulation by 3-Phosphoinositide-Dependent Protein Kinase 1 and Ser473 Kinase

1999 ◽  
Vol 19 (7) ◽  
pp. 5061-5072 ◽  
Author(s):  
Mirjana Andjelković ◽  
Sauveur-Michel Maira ◽  
Peter Cron ◽  
Peter J. Parker ◽  
Brian A. Hemmings
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Protein Kinase B ◽  
Second Messengers ◽  
Activation Mechanism ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Phosphoinositide 3 Kinase ◽  
Regulatory Sites

ABSTRACT Protein kinase B (PKB or Akt), a downstream effector of phosphoinositide 3-kinase (PI 3-kinase), has been implicated in insulin signaling and cell survival. PKB is regulated by phosphorylation on Thr308 by 3-phosphoinositide-dependent protein kinase 1 (PDK1) and on Ser473 by an unidentified kinase. We have used chimeric molecules of PKB to define different steps in the activation mechanism. A chimera which allows inducible membrane translocation by lipid second messengers that activate in vivo protein kinase C and not PKB was created. Following membrane attachment, the PKB fusion protein was rapidly activated and phosphorylated at the two key regulatory sites, Ser473 and Thr308, in the absence of further cell stimulation. This finding indicated that both PDK1 and the Ser473 kinase may be localized at the membrane of unstimulated cells, which was confirmed for PDK1 by immunofluorescence studies. Significantly, PI 3-kinase inhibitors prevent the phosphorylation of both regulatory sites of the membrane-targeted PKB chimera. Furthermore, we show that PKB activated at the membrane was rapidly dephosphorylated following inhibition of PI 3-kinase, with Ser473 being a better substrate for protein phosphatase. Overall, the results demonstrate that PKB is stringently regulated by signaling pathways that control both phosphorylation/activation and dephosphorylation/inactivation of this pivotal protein kinase.

scholarly journals Identification of a PKB/Akt Hydrophobic Motif Ser-473 Kinase as DNA-dependent Protein Kinase

2004 ◽  
Vol 279 (39) ◽  
pp. 41189-41196 ◽  
Author(s):  
Jianhua Feng ◽  
Jongsun Park ◽  
Peter Cron ◽  
Daniel Hess ◽  
Brian A. Hemmings
Keyword(s):  
Protein Kinase ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Hydrophobic Motif

scholarly journals Activation of protein kinase B β and γ isoforms by insulin in vivo and by 3-phosphoinositide-dependent protein kinase-1 in vitro: comparison with protein kinase B α

1998 ◽  
Vol 331 (1) ◽  
pp. 299-308 ◽  
Author(s):  
Kay S. WALKER ◽  
Maria DEAK ◽  
Andrew PATERSON ◽  
Kevin HUDSON ◽  
Philip COHEN ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Protein Kinase B ◽  
Rat Hepatocytes ◽  
Dependent Protein Kinase ◽  
L6 Myotubes ◽  
Dependent Protein ◽  
Stimulation Of

The regulatory and catalytic properties of the three mammalian isoforms of protein kinase B (PKB) have been compared. All three isoforms (PKBα, PKBβ and PKBγ) were phosphorylated at similar rates and activated to similar extents by 3-phosphoinositide-dependent protein kinase-1 (PDK1). Phosphorylation and activation of each enzyme required the presence of PtdIns(3,4,5)P3 or PtdIns(3,4)P2, as well as PDK1. The activation of PKBβ and PKBγ by PDK1 was accompanied by the phosphorylation of the residues equivalent to Thr308 in PKBα, namely Thr309 (PKBβ) and Thr305 (PKBγ). PKBγ which had been activated by PDK1 possessed a substrate specificity identical with that of PKBα and PKBβ towards a range of peptides. The activation of PKBγ and its phosphorylation at Thr305 was triggered by insulin-like growth factor-1 in 293 cells. Stimulation of rat adipocytes or rat hepatocytes with insulin induced the activation of PKBα and PKBβ with similar kinetics. After stimulation of adipocytes, the activity of PKBβ was twice that of PKBα, but in hepatocytes PKBα activity was four-fold higher than PKBβ. Insulin induced the activation of PKBα in rat skeletal muscle in vivo, with little activation of PKBβ. Insulin did not induce PKBγ activity in adipocytes, hepatocytes or skeletal muscle, but PKBγ was the major isoform activated by insulin in rat L6 myotubes (a skeletal-muscle cell line).

scholarly journals Activation Mechanism of Protein Kinase B by DNA-dependent Protein Kinase Involved in the DNA Repair System

2008 ◽  
Vol 24 (3) ◽  
pp. 175-182 ◽  
Author(s):  
Yuwen Li ◽  
Longzhen Piao ◽  
Keum-Jin Yang ◽  
Sang-Hee Shin ◽  
Eul-Soon Shin ◽  
...  
Keyword(s):  
Dna Repair ◽  
Protein Kinase ◽  
Protein Kinase B ◽  
Activation Mechanism ◽  
Repair System ◽  
Dependent Protein Kinase ◽  
Dependent Protein

scholarly journals Full Activation of Kinase Protein Kinase B by Phosphoinositide-Dependent Protein Kinase-1 and Mammalian Target of Rapamycin Complex 2 Is Required for Early Natural Killer Cell Development and Survival

2021 ◽  
Vol 11 ◽  
Author(s):  
Junming He ◽  
Jun Zhao ◽  
Yuhe Quan ◽  
Xinlei Hou ◽  
Meixiang Yang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nk Cells ◽  
Nk Cell ◽  
Protein Kinase B ◽  
Killer Cell ◽  
Cell Development ◽  
Developmental Defect ◽  
Dependent Protein Kinase ◽  
Dependent Protein

The role of PI3K-mTOR pathway in regulating NK cell development has been widely reported. However, it remains unclear whether NK cell development depends on the protein kinase B (PKB), which links PI3K and mTOR, perhaps due to the potential redundancy of PKB. PKB has two phosphorylation sites, threonine 308 (T308) and serine 473 (S473), which can be phosphorylated by phosphoinositide-dependent protein kinase-1 (PDK1) and mTORC2, respectively. In this study, we established a mouse model in which PKB was inactivated through the deletion of PDK1 and Rictor, a key component of mTORC2, respectively. We found that the single deletion of PDK1 or Rictor could lead to a significant defect in NK cell development, while combined deletion of PDK1 and Rictor severely hindered NK cell development at the early stage. Notably, ectopic expression of myristoylated PKB significantly rescued this defect. In terms of mechanism, in PDK1/Rictor-deficient NK cells, E4BP4, a transcription factor for NK cell development, was less expressed, and the exogenous supply of E4BP4 could alleviate the developmental defect of NK cell in these mice. Besides, overexpression of Bcl-2 also helped the survival of PDK1/Rictor-deficient NK cells, suggesting an anti-apoptotic role of PKB in NK cells. In summary, complete phosphorylation of PKB at T308 and S473 by PDK1 and mTORC2 is necessary for optimal NK cell development, and PKB regulates NK cell development by promoting E4BP4 expression and preventing cell apoptosis.

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