Characterization of the bovine prion protein gene: the expression requires interaction between the promoter and intron.

We cloned the part of the bovine PrP gene which contains the 5'-flanking region, exon 1, exon 2 and intron 1 to analyze its promoter region. The 5' non-coding region of the bovine PrP gene consisted of three exons and two introns, and its organization was similar to that of the mouse, rat and sheep PrP genes. The 5'-flanking region of the bovine PrP gene from the transcription start site to nucleotide position -88 was (G + C)-rich (78%) and contained three potential binding sites for the transcription factor Sp1, but no CCAAT-box or TATA-box. This region showed high homology (89%) with that of the sheep PrP gene, but relatively low homology (approximately 46-62%) with the same region of the mouse, rat, hamster and human PrP genes. The position from -88 to -30 within the 5'-flanking region of the bovine PrP gene showed major promoter activity. However, this region was able to function properly only in collaboration with the region at +123 to +891 of intron 1 of the bovine PrP gene.