Localization of the feline sarcoma virus fgr gene product (P70gag-actin-fgr): association with the plasma membrane and detergent-insoluble matrix.
The v-fgr oncogene codes for a unique transforming protein (P70gag-actin-fgr) that contains virus-specific determinants and cell-derived sequences for both a tyrosine-specific kinase domain and an actin domain. We examined the subcellular distribution of the v-fgr protein by immunofluorescence microscopy and various cell fractionation techniques. By immunofluorescence, the v-fgr protein was localized in a diffuse cytoplasmic pattern within transformed cells. The v-fgr protein was not detectable at substratum adhesion sites. Crude membrane preparations (P100) obtained from fgr-transformed cells contained elevated levels of P70gag-actin-fgr. Further analysis of membranes on discontinous sucrose gradients revealed that P70gag-actin-fgr cofractionated with plasma membranes. Using an alternate method of fractionation, we found that the majority of the v-fgr protein remained with the insoluble matrix obtained by treating cells with a buffer containing Triton X-100. When membranes were similarly treated with detergent, nearly all of v-fgr protein remained with the residual insoluble matrix. These results suggest that the transforming activity of P70gag-actin-fgr may be directed to subcellular cytoskeletal targets at or near the cytoplasmic face of the plasma membrane.
D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D015683:Gene Products, gag; D005814:Genes, Viral; D008907:Mink; D008970:Molecular Weight; D009226:Myristates / Q000378:metabolism; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D012190:Retroviridae / Q000378:metabolism*; D012191:Retroviridae Proteins / Q000235:genetics / Q000378:metabolism*; D005253:Sarcoma Viruses, Feline / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D015683:Gene Products, gag; D009226:Myristates; D009856:Oncogene Proteins, Viral; D012191:Retroviridae Proteins; D011505:Protein-Tyrosine Kinases