Nucleotide sequence of the chicken proto-oncogene c-erbA corresponding to domain 1 of v-erbA

The nucleotide sequence of the chicken proto-oncogene c-erbA, the cellular counterpart of the viral oncogene v-erbA domain 1, has been determined. The c-erbA gene has an exon-intron structure characteristic of the eukaryotic split genes. The c-erbA domain 1 is composed of at least eight exons and seven introns. Analysis of the sequence data reveals a long open reading frame of 239 amino acid residues that share highly significant homology with the viral protein. Our results show that the viral erbA oncogene is a truncated form of its cellular homologue. In fact the cellular gene is 42 nucleotides longer at its 5' coding extremity. The presence of a gag-specific (17/20) nucleotide stretch in this region favours the hypothesis of a homologous recombination event between the cellular erbA and the gag gene of a parental retrovirus. We have also sequenced 1400 bp of DNA lying 5' to the long open reading frame in search of the transcription initiation sites for the c-erbA messenger RNAs. Our findings and interpretations are presented here.