title: Phosphorylation of the p190 RhoGAP N-terminal domain by c-Src results in a loss of GTP binding activity.
abstract: p190 RhoGAP is a multi-domain protein that is thought to regulate actin cytoskeleton dynamics. It can be phosphorylated both in vitro and in vivo at multiple sites by the Src tyrosine kinase and one or more of these sites is postulated to modulate p190 function. One of the regions which is multiply phosphorylated by Src in vitro is the N-terminal GTP binding domain. Using a partially purified, bacterially expressed recombinant protein that includes the GTP binding domain (residues 1-389), we show that GTP binds to this fragment in a specific and saturable manner that is both time- and dose-dependent and that tyrosine phosphorylation of this fragment by c-Src results in a loss of GTP binding activity. These findings suggest that tyrosine phosphorylation of the p190 N-terminal domain can alter its ability to bind GTP.
authors.affiliation: Department of Microbiology and Cancer Center, University of Virginia, P.O. Box 441, Charlottesville, VA 22908, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Roof
authors.forename: B D
authors.initials: BD
authors.lastname: Dukes
authors.forename: J H
authors.initials: JH
authors.lastname: Chang
authors.forename: S J
authors.initials: SJ
authors.lastname: Parsons
mesh_terms: D000595:Amino Acid Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; D010750:Phosphoproteins; D016392:Proto-Oncogene Proteins pp60(c-src); D019204:GTP-Binding Proteins