Organization of 5'-proximal c-myb exons in chicken DNA. Implications for c-myb tissue-specific transcription.

The organization of 5'-proximal c-myb exons in chicken DNA has been established by restriction enzyme mapping and nucleotide sequencing. Hybridization studies performed with cDNA probes revealed that yolk sac and thymic c-myb RNAs differ in their 5'-termini. A comparison of the genomic c-myb sequence with that of cDNAs isolated from normal thymic and lymphoma avian cells suggests that different promoter regions are used to initiate c-myb transcription in hematopoietic cells of different origins.