Human Cellular Fps/fes CDNA Rescued Via Retroviral Shuttle Vector Encodes Myeloid Cell NCP92 and Has Transforming Potential

We have generated a cDNA copy of human c-fps/fes from a 13 kb genomic DNA by means of a retroviral shuttle vector, and have begun characterization of its biological and biochemical properties. The cDNA was able to direct the in vitro synthesis of a protein that was indistinguishable from myeloid cell c-fps/fes NCP92 by immunoprecipitation with specific antisera, electrophoretic mobility, tryptic fingerprint analysis, and its associated protein kinase activity. When the coding sequence of the gag-v-fps/fes P108 fusion protein in Gardner Arnstein Feline sarcoma virus was substituted with the recovered cDNA, the recombinant plasmid directed the expression of NCP92 in NIH 3T3 cells but no morphological transformation was observed. By contrast, when viral gag sequences were linked to the N-terminus of NCP92, the chimeric gene induced foci of transformed cells. These transformants were capable of anchorage independent growth, were tumorigenic in nude mice, and expressed a gag fusion protein kinase of high specific activity. The biological properties of this recombinant are discussed. We conclude that normal human c-fps/fes can be activated by N-terminal linkage to gag.