Influence of tyrosine residues Y705 and Y807 on the transforming potency of the v-fms oncogene product of feline sarcoma virus.

Cell transformation is characterized by overt changes in growth control and cell morphology. To study the role of tyrosine residues Y705 and Y807 of v-Fms of the McDonough strain of feline sarcoma virus in cell transformation we replaced them individually with phenylalanine residues. Cells expressing the mutant genes showed mitogenic properties similar to wild-type v-Fms transformed cells. However, the morphology of cells expressing the Y807F mutant remained the same as nontransformed cells. Four phosphoproteins of 190, 120, 55 and 50 kDa were detected in cells expressing the wild-type but were absent in cells expressing the mutant Y807F-v-fms gene.