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KMID : 0613820070170020185
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Journal of Life Science
2007 Volume.17 No. 2 p.185 ~ p.191
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Direct tyrosine phosphorylation of Akt/PKB by epidermal growth factor receptor
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Bae Sun-Sik
Choi Jang-Hyun
Yun Sung-Ji
Kim Eun-Kyung
Oh Yong-Suk
Kim Chi-Dae
Suh Pan-Ghil
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Abstract
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Akt/PKB plays pivotal roles in many physiological responses such as proliferation, differentiation, apoptosis, and angiogenesis. Here we show that tyrosine phosphorylation of Akt/PKB is essential for the subsequent phosphorylation at Thr308. Tyrosine phosphorylation of Akt/PKB was induced by stimulation of COS-7 cells with epidermal growth factor receptor (EGF) and its phosphorylation was significantly enhanced by constitutive targeting of Akt/PKB to the plasma membrane by myristoylation. Interestingly, incubation of affinity purified Myc-tagged Akt/PKB with purified EGF receptor resulted in tyrosine phosphorylation as well as Ser473 phosphorylation of Akt/PKB. In addition, tyrosine-phosphorylated Akt/PKB could directly associate with activated EGF receptor in vitro. Finally, alanine mutation at putative tyrosine phosphorylation site (Tyr326) abolished EGF induced Thr308 phosphorylation of wild type as well as constitutively active form of Akt/PKB. Given these results we suggest here that direct tyrosine phosphorylation of Akt/PKB by EGF receptor could be another mechanism of EGF-induced control of many physiological responses.
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KEYWORD
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Akt/PKB, Epidermal growth factor receptor, tyrosine phosphorylation, survival, growth
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