Amino acid availability regulates p70 S6 kinase and multiple translation factors

Wang, Xuemin and Campbell, L.E. and Miller, C.M. and Proud, Christopher G. (1998) Amino acid availability regulates p70 S6 kinase and multiple translation factors. Biochemical Journal, 334 (Part 1). pp. 261-267. ISSN 0264-6021. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Incubation of Chinese hamster ovary cells without amino acids for up to 60 min caused a rapid marked decrease in p70 S6 kinase activity and increased binding of initiation factor eIF4E to its inhibitory regulator protein 4E-BP1. This was associated with dephosphorylation of 4E-BP1 and eIF4E and dissociation of eIF4E from eIF4G. All these effects were rapidly reversed by resupplying a mixture of amino acids and this was blocked by rapamycin and by inhibitors of phosphatidylinositol 3-kinase, implying a role for phosphatidylinositol 3-kinase in the signalling pathway linking amino acids with the control of p70 S6 kinase activity and the phosphorylation of these translation factors. Amino acid withdrawal also led to changes in the phosphorylation of other translation factors; phosphorylation of eIF4E decreased whereas elongation factor eEF2 became more heavily phosphorylated, each of these changes being associated with decreased activity of the factor in question. Earlier studies have suggested that protein kinase B (PKB) may act upstream of p70 S6 kinase. However, amino acids did not affect the activity of PKB, indicating that amino acids activate p70 S6 kinase through a pathway independent of this enzyme. Studies with individual amino acids suggested that the effects on p70 S6 kinase activity and translation-factor phosphorylation were independent of cell swelling. The data show that amino acid supply regulates multiple translation factors in mammalian cells.

Item Type: Article
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Tara Puri
Date Deposited: 31 May 2009 18:22
Last Modified: 11 Jun 2014 08:37
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