IndraLab

"The PKB Y315 residue, which is known to be phosphorylated by Src tyrosine kinase, was also a major site of phosphorylation by RET/PTC. RET/PTC-mediated tyrosine phosphorylation results in the activation of PKB kinase activity"

"Here we demonstrate that AKT is a direct substrate of PTK6 and that AKT tyrosine residues 315 and 326 are phosphorylated by PTK6."

"These observations suggest that RET/PTC is able to phosphorylate the Y315 residue of PKB, an event that results in maximal activation of PKB for RET/PTC-induced thyroid tumorigenesis."

"Regulation of Akt/PKB Activation by Tyrosine PhosphorylationAs shown in Fig. 2 d, while mutation of Tyr340 has little effect on either tyrosine phosphorylation or kinase activity of Akt induced by Src527F, substitution of Tyr315 or Tyr326 with a phenylalanine, respectively, dramatically reduces both the tyrosine phosphorylation and kinase activity of Akt. The combination of these two mutations abolishes Src-induced tyrosine phosphorylation of Akt as well as its kinase activity."

"We also showed that phosphorylation of Tyr-315 in Akt induced by Src or EGF is dependent on the integrity of this proline-rich motif. Furthermore, the Akt mutant lacking this proline motif fails to block the transcription activity of Forkhead in 293 cells and poorly stimulates the proliferation of Madin-Darby canine kidney cells. Taken together, our data suggest that the interaction between the SH3 domain of Src family kinases and the proline-rich motif in the C-terminal regulatory region of Akt is required for tyrosine phosphorylation of Akt and its subsequent activation."