Isolation and characterization of c-myc, a cellular homolog of the oncogene (v-myc) of avian myelocytomatosis virus strain 29

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Abstract
The chicken genome contains nucleotide sequences homologous to the transforming genes (oncogenes) of a number of avian retroviruses. Chicken DNA (c-myc) that is homologous to the oncogene (v-myc) of the avian myelocytomatosis virus MC29 was isolated, and the structures of the cellular and viral genes were compared. Results from restriction endonuclease mapping of c-myc and from analysis of heteroduplexes between the DNA of the cellular and viral genes show that c-myc is homologous to 1500 nucleotides in v-myc DNA. This homologous region is interrupted in c-myc by an intron-like sequence of 1100 nucleotides which is absent from v-myc. Nuclear RNA from normal chicken cells contains at least 5 species of transcripts from c-myc ranging from 2.5 to 6.5 kilobases [kb] in length. Cytoplasm contains only the 2.5-kb c-myc RNA. These features of the c-myc gene and its nuclear transcripts are characteristic of normal cellular genes and suggest that the myc gene is of cellular rather than viral origin. The exons in c-myc may define 2 functional domains in the gene and may therefore facilitate the dissection of the different oncogenic potentials of the MC29 virus.