The nucleotide sequence of an 8.2-kb DNA fragment from the 5' proximal part of the chicken myb proto-oncogene spanning 1761 nucleotides upstream and 6436 nucleotides downstream from a presumed c-myb initiation codon was determined. A 3.3-kb G + C-rich region found in this sequence had also other features characterizing CpG islands, i.e. no CpG underrepresentation and lack of CpG methylation. In haematopoietic tissues c-myb mRNA synthesis starts in two major regions of the CpG island, namely 98 to 108 and 143 to 145 nucleotides upstream from the c-myb initiation codon. These two regions are in or close to the 124-bp evolutionarily conserved element located in the middle part of the CpG island. No alternative splicing of the 5' end of c-myb mRNA suggested earlier (1,2) was observed. The c-myb promoter contains neither TATA nor CAAT box-like structures at the usual positions. Instead, numerous potential Sp1 factor binding sites were found both upstream and downstream from the transcription initiation sites. Moreover, consensus v-myb protein DNA-binding sites were revealed in the promoter region and in sequences downstream from it.

• MeSH
• Dinucleoside Phosphates analysis   MeSH
• Single-Strand Specific DNA and RNA Endonucleases MeSH
• Endonucleases MeSH
• Erythrocytes analysis   MeSH
• Transcription, Genetic * MeSH
• Cloning, Molecular MeSH
• Chickens MeSH
• Molecular Sequence Data MeSH
• Mice MeSH
• Organ Specificity MeSH
• Promoter Regions, Genetic MeSH
• Proto-Oncogene Proteins c-myb MeSH
• Proto-Oncogene Proteins genetics   MeSH
• Proto-Oncogenes * MeSH
• Restriction Mapping MeSH
• RNA Caps genetics   MeSH
• Base Sequence MeSH
• Sequence Homology, Nucleic Acid MeSH
• Thymus Gland analysis   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Names of Substances
• cytidylyl-3'-5'-guanosine MeSH Browser
• Dinucleoside Phosphates MeSH
• Single-Strand Specific DNA and RNA Endonucleases MeSH
• Endonucleases MeSH
• Proto-Oncogene Proteins c-myb MeSH
• Proto-Oncogene Proteins MeSH
• RNA Caps MeSH

The nucleotide sequence of the chicken myb proto-oncogene putative promoter region was determined and compared with the corresponding sequence of the mouse c-myb gene (1). 118 bp upstream from the initiation codon suggested by Gerondakis and Bishop (2) for the chicken c-myb protein, a 124-bp-long conserved element was found (92% identity in chicken and mouse sequences). Sequences homologous to this element were detected on Southern blots of restricted genomic DNAs from mouse, man, lizard, frog, and carp. No hybridization was observed with Drosophila, yeast, or Escherichia coli DNA. In human DNA, sequences homologous to this element were located at the 5' end of the c-myb gene, i.e. in the same position as in the chicken and mouse genes. Several lines of evidence suggest that the element is not a coding exon of a gene overlapping the c-myb gene. It may be of importance that one of the DNase I-sensitive sites and several c-myb mRNA cap sites localized recently in the mouse c-myb gene (3,4) lie within this region. It is suggested that this evolutionarily conserved element is involved in the regulation of myb proto-oncogene expression in vertebrates.

• MeSH
• Biological Evolution * MeSH
• Drosophila melanogaster MeSH
• Lizards MeSH
• Carps MeSH
• Chickens MeSH
• Humans MeSH
• Molecular Sequence Data MeSH
• Mice MeSH
• Promoter Regions, Genetic * MeSH
• Proto-Oncogene Mas MeSH
• Proto-Oncogenes * MeSH
• Base Sequence * MeSH
• Sequence Homology, Nucleic Acid * MeSH
• Cattle MeSH
• Xenopus laevis MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Cattle MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH