Human dbl proto-oncogene in 85 kb of xq26, and determination of the transcription initiation site.
The dbl oncogene is generated by substitution of the 5' portion of its normal counterpart with an unrelated human sequence. To analyze the genomic structure and transcriptional regulation of the dbl proto-oncogene, we have isolated human genomic clones containing the entire human proto-dbl gene, localized in Xq26. Restriction mapping of a 600kb YAC clone (yWXD311) placed proto-dbl about 50kb telomeric to the coagulation Factor IX gene. The genomic DNA fragment containing the 5' end of proto-dbl was subcloned into plasmid vectors and the nucleotide sequences of exon 1, the flanking intronic region and genomic DNA 5' of the first codon were determined. Sequence analysis of 85119bp from the region revealed the genomic structure of proto-dbl. It contains 25 exons coding for a 4.7kb transcript including large 5'- and 3'- (1218bp and 701bp, respectively) untranslated regions (UTRs). RNase protection and primer extension assays on RNA from medullary thyroid carcinoma (TT) cells, which normally express dbl, revealed a transcription start site 1218bp upstream of the ATG of the first exon. A 1.6kb genomic 5' of the translation start sites drives the expression of a CAT-reporter in transient transfections in the TT cell line, though lacking TATA or CAAT boxes.
Palmieri
G
G
International Institute of Genetics and Biophysics, C.N.R., Via Marconi 10, Naples, Italy.
de Franciscis
V
V
Casamassimi
A
A
Romano
G
G
Torino
A
A
Pingitore
P
P
Califano
D
D
Santelli
G
G
Eva
A
A
Vecchio
G
G
D'Urso
M
M
Ciccodicola
A
A
D001483:Base Sequence; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005091:Exons; D005796:Genes / Q000235:genetics; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D007438:Introns; D011401:Promoter Regions, Genetic; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D014960:X Chromosome / Q000235:genetics*
D020662:Guanine Nucleotide Exchange Factors; C000715470:MAS1 protein, human; C057811:MCF2 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D004247:DNA; D015500:Chloramphenicol O-Acetyltransferase