A mutation in v-src that removes a single conserved residue in the SH-2 domain of pp60v-src restricts transformation in a host-dependent manner.
The v-src oncogene of Rous sarcoma virus (RSV) is able to transform both avian and mammalian cells, but the mutant allele v-src-L displays a host range dependence for transformation, transforming chicken but not rat cells with wild-type efficiency. This host range restriction can be detected by measuring growth in low serum, saturation density, and anchorage independent growth. In addition, rat cells expressing v-src-L do not form tumors in syngeneic rats or nude mice, but RSV carrying the mutant allele causes tumors in chicks, although at a reduced efficiency and with increased latency. To determine the lesion responsible for this phenotype, we sequenced the entire v-src gene from the parental B77 strain of RSV, as well as the mutant allele. v-src-L is missing 3 nucleotides present in the wild-type parent, RSV B31, eliminating Phe-172, an invariant residue in a conserved region of src-related proteins known as SH-2. The kinase activity of pp60v-src-L was indistinguishable from that of the wild type in chicken cells but was significantly reduced in rat cells as assayed by an in vitro immune complex assay; in vivo phosphorylation of one specific substrate, p36 (calpactin I heavy chain); and total phosphotyrosine-containing proteins. In addition, the pattern of phosphotyrosine-containing proteins in rat cells was qualitatively different when cells containing pp60v-src-L were compared with cells with wild-type pp60v-src, even though both pp60v-src proteins were membrane associated. The data are consistent with a role for the SH-2 region in substrate specificity.
Verderame
M F
MF
Department of Microbiology and Immunology, University of California, San Francisco 94118.
Kaplan
J M
JM
Varmus
H E
HE
D000483:Alleles; D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D002455:Cell Division; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D002642:Chick Embryo; D004279:DNA, Viral / Q000235:genetics; D007739:L Cells; D008969:Molecular Sequence Data; D009154:Mutation; D015688:Oncogene Protein pp60(v-src); D009857:Oncogenes; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D012191:Retroviridae Proteins / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
D004279:DNA, Viral; D012191:Retroviridae Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src)