Mutagenesis of Fujinami sarcoma virus: evidence that tyrosine phosphorylation of P130gag-fps modulates its biological activity

Cell. 1984 Jun;37(2):559-68. doi: 10.1016/0092-8674(84)90386-6.


The 130 kd transforming protein of Fujinami sarcoma virus (FSV P130gag -fps) possesses a tyrosine-specific protein kinase activity and is itself phosphorylated at several tyrosine and serine residues in FSV-transformed cells. We have used oligonucleotide-directed mutagenesis of the FSV genome to change the TAT codon for tyrosine (1073), the major site of P130gag -fps phosphorylation, to a TTT codon for phenylalanine that cannot be phosphorylated. This mutant FSV induces the transformation of rat-2 cells but with a long latent period as compared with wild-type FSV. The P130gag -fps protein encoded by the mutant retains the ability to phosphorylate tyrosine, but is five times less active as a kinase in vitro than wild-type FSV P130gag -fps. These data indicate that tyrosine phosphorylation stimulates the biochemical and biological activities of FSV P130gag -fps, and they set a precedent for the ability of this amino acid modification to modulate protein function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, Viral / genetics*
  • Avian Sarcoma Viruses / genetics*
  • Base Sequence
  • Cell Line
  • Cell Transformation, Neoplastic
  • DNA Restriction Enzymes
  • Gene Products, gag
  • Mutation*
  • Phosphorylation
  • Protein Kinases / genetics*
  • Protein-Tyrosine Kinases
  • Transfection
  • Tyrosine
  • Viral Proteins / genetics*


  • Antigens, Viral
  • Gene Products, gag
  • Viral Proteins
  • Tyrosine
  • Protein Kinases
  • Protein-Tyrosine Kinases
  • DNA Restriction Enzymes