title: Nucleotide sequence 5' of the chicken c-myc coding region: localization of a noncoding exon that is absent from myc transcripts in most avian leukosis virus-induced lymphomas.
abstract: We have determined the nucleotide sequence of the 2.2-kilobase-pair region upstream of the chicken c-myc coding exons. Using RNA blot analysis, we have localized a noncoding exon to a region that is separated from the c-myc coding sequences by an intron of 700-800 base pairs. In most avian leukosis virus-induced lymphomas proviral integration has occurred within, or downstream of, the first exon, thus presumably displacing the regulatory sequences that normally control c-myc expression. More than 70% of the integration sites were clustered in a 250-base-pair region in the first intron, immediately preceding the coding sequences. Sequences from the upstream noncoding exon were absent from the myc transcripts in these lymphomas; RNA transcripts from the normal c-myc allele were not expressed at detectable levels.
mesh_terms: D000818:Animals; D001354:Avian Leukosis Virus / Q000235:genetics*; D001483:Base Sequence; D002472:Cell Transformation, Viral; D002645:Chickens; D005796:Genes; D008223:Lymphoma / Q000235:genetics / Q000382:microbiology; D009857:Oncogenes; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger