Isolation of the proto-oncogene c-myb from D. melanogaster.

We have isolated the proto-oncogene c-myb from Drosophila melanogaster. This gene is represented by a single locus at position 13E-F on the X chromosome, and is expressed in early embryos by transcription into two polyadenylated RNAs with lengths of approximately 3.0 and 3.8 kb. The gene may encode a protein with a molecular weight of at least 55,000 that shares a domain with c-myb (chicken) in which 91 of 125 (or 73%) of the amino acids are identical in the Drosophila and chicken genes. These findings represent the first rigorous identification of a Drosophila proto-oncogene that can encode what may be a nuclear protein, and they set the stage for a genetic analysis of how c-myb serves the normal organism.