Two new retroviral onc genes, sea and jun.

Avian leukemia virus S13 induces erythroblastosis, granulocytic leukemia, fibrosarcoma, anemia, and endothelial neoplasia. It transforms chick embryo fibroblasts and primitive erythroid cells in culture and is defective in replication. Its onc gene, sea, is expressed as transformation specific env-sea fusion glycoprotein of 155 kDa. Gp155 is proteolytically processed into gp85env and gp70env-sea. The latter shows tyrosine specific protein kinase activity. Avian sarcoma virus 17 induces fibrosarcoma and transforms chick embryo fibroblasts in culture. Its cell derived onc gene, jun, is not related to known onc genes and appears to be expressed as a gag-jun fusion protein of 55 kDa. The amino acid sequence of jun shows homology in its C-terminal region to the C-terminal DNA binding region of the yeast regulatory protein GCN4, suggesting that the jun protein may bind to DNA.