Abstract
We have identified a rapid protein phosphorylation event at residue serine 16 of stathmin using two-dimensional gel electrophoresis coupled to matrix-assisted laser desorption/ionization mass spectrometry in combination with post-source decay analysis, which is induced by the epidermal growth factor receptor. Phosphorylation is specifically mediated by the small GTPases Rac and Cdc42 and their common downstream target, the serine/threonine kinase p65PAK. Both GTPases have previously been shown to regulate the dynamics of actin polymerization. Because stathmin destabilizes microtubules, and this process is inhibited by phosphorylation at residue 16, Rac and Cdc42 can potentially regulate both F-actin and microtubule dynamics.
Highlights
EGF1 leads to the phosphorylation of stathmin at residue 16
Phosphorylation at this site has been shown to inhibit stathmin-induced destabilization of microtubules, and our results suggest, that Rac and Cdc42 can regulate the dynamics of both the actin and the microtubule cytoskeletons [5, 6]
We have identified a rapid protein phosphorylation event at residue serine 16 of stathmin using two-dimensional gel electrophoresis coupled to matrix-assisted laser desorption/ionization mass spectrometry in combination with post-source decay analysis, which is induced by the epidermal growth factor receptor
Summary
EGF1 leads to the phosphorylation of stathmin at residue 16 Phosphorylation at this site has been shown to inhibit stathmin-induced destabilization of microtubules, and our results suggest, that Rac and Cdc can regulate the dynamics of both the actin and the microtubule cytoskeletons [5, 6]. Phosphorylation is mediated by the small GTPases Rac and Cdc and their common downstream target, the serine/threonine kinase p65PAK Both GTPases have previously been shown to regulate the dynamics of actin polymerization. Members of the Rho GTPase family, Rho, Rac, and Cdc, control the assembly of filamentous actin structures in all mammalian cells [1] Their ability to link extracellular signals to the reorganization of the actin cytoskeleton suggests that they are likely to be important regulators of actin-driven cell processes, and Rac, for example, is crucial for growth cone guidance and cell migration both in tissue culture cells and in vivo in Drosophila and Caenorhabditis elegans [2,3,4].
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