title: Expression cloning of a human dual-specificity phosphatase.
abstract: Using an expression cloning strategy, we isolated a cDNA encoding a human protein-tyrosine-phosphatase. Bacteria expressing the kinase domain of the keratinocyte growth factor receptor (bek/fibroblast growth factor receptor 2) were infected with a fibroblast cDNA library in a phagemid prokaryotic expression vector and screened with a monoclonal anti-phosphotyrosine antibody. Among several clones showing decreased anti-phosphotyrosine recognition, one displayed phosphatase activity toward the kinase in vitro. The 4.1-kilobase cDNA encoded a deduced protein of 185 amino acids with limited sequence similarity to the vaccinia virus phosphatase VH1. The purified recombinant protein dephosphorylated several activated growth factor receptors, as well as serine-phosphorylated casein, in vitro. Both serine and tyrosine phosphatase activities were completely abolished by mutagenesis of a single cysteine residue conserved in VH1 and the VH1-related (VHR) human protein. These properties suggest that VHR is capable of regulating intracellular events mediated by both tyrosine and serine phosphorylation.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D010768:Phosphoserine / Q000378:metabolism; D019000:Phosphotyrosine; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D016415:Sequence Alignment; D013379:Substrate Specificity; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine; D010749:Phosphoprotein Phosphatases