Characterization of the 5' region of the Atlantic salmon (Salmo salar) transferrin-encoding gene.

A genomic fragment encompassing the first two exons and 1.3-kb 5'-flanking sequence of the Atlantic salmon transferrin (Tf)-encoding gene (sTf) has been isolated and characterized. The transcription start point of sTf was mapped to 48 nucleotides upstream from the translation start codon. In the proximal promoter region (-118 to +1), sTf displays sequence similarity to the chicken, mouse and human Tf, and contains a TATA-box, CCAAT-box and CAAAC motif conserved during evolution. Putative binding sites for the transcription factors AP-2, AP-3, Sp1, CF1, NF-IL6, HNF-5, GCF and GATA-1 were identified in the sTf 5'-flanking sequence. An element with dyad symmetry is located between -219 and -201, and an alternating purine-pyrimidine (APP) sequence (a 24-bp imperfect CA repeat) is located at -187 to -164. A minisatellite consisting of 25 tanden repeats of a 37-bp motif occupies the region between -1338 and -417. The Atlantic salmon has two Tf genes. Comparison of the 5'-end sequences (nt -383 to +80) of the two sTf revealed only minor differences, except that the length of a CA repeat differs by 12 bp.