Protein-tyrosine kinase and GTPase signals cooperate to phosphorylate and activate Wiskott-Aldrich syndrome protein (WASP)/neuronal WASP
Program in Gene Function and Expression; Program in Molecular Medicine
Medical Subject Headings
Actins; Animals; Cattle; Cytoskeleton; Enzyme Activation; GTP Phosphohydrolases; Humans; Kinetics; Lymphocyte Specific Protein Tyrosine Kinase p56(lck); Models, Biological; Neurons; Nitric Oxide Synthase Type I; Phosphorylation; Polymers; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Protein-Tyrosine Kinases; Wiskott-Aldrich Syndrome Protein; Wiskott-Aldrich Syndrome Protein Family; Wiskott-Aldrich Syndrome Protein, Neuronal; cdc42 GTP-Binding Protein; src Homology Domains
Biochemistry | Cellular and Molecular Physiology | Genetics and Genomics | Molecular Biology
Protein-tyrosine kinases and Rho GTPases regulate many cellular processes, including the reorganization and dynamics of the actin cytoskeleton. The Wiskott-Aldrich syndrome protein (WASP) and its homolog neuronal WASP (N-WASP) are effectors of the Rho GTPase Cdc42 and provide a direct link between activated membrane receptors and the actin cytoskeleton. WASP and N-WASP are also regulated by a large number of other activators, including protein-tyrosine kinases, phosphoinositides, and Src homology 3-containing adaptor proteins, and can therefore serve as signal integrators inside cells. Here we show that Cdc42 and the Src family kinase Lck cooperate at two levels to enhance WASP activation. First, autoinhibition in N-WASP decreases the efficiency (kcat/Km) of phosphorylation and dephosphorylation of the GTPase binding domain by 30- and 40-fold, respectively, and this effect is largely reversed by Cdc42. Second, Cdc42 and the Src homology 3-Src homology 2 module of Lck cooperatively stimulate the activity of phosphorylated WASP, with coupling energy of approximately 2.4 kcal/mol between the two activators. These combined effects provide mechanisms for high specificity in WASP activation by coincident GTPase and kinase signals.
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Citation: J Biol Chem. 2006 Feb 10;281(6):3513-20. Epub 2005 Nov 17. Link to article on publisher's site
Torres, Eduardo M. and Rosen, Michael K., "Protein-tyrosine kinase and GTPase signals cooperate to phosphorylate and activate Wiskott-Aldrich syndrome protein (WASP)/neuronal WASP" (2006). Program in Gene Function and Expression Publications and Presentations. 224.