Conserved dyad symmetry structures at the 3' end of H5 histone genes. Analysis of the duck H5 gene.

The duck H5 histone gene and its flanking DNA have been isolated and sequenced. S1 nuclease mapping reveals that transcription starts 149 nucleotides upstream of the initiation codon and that the site of polyadenylation is located 200 nucleotides downstream of the termination codon. A comparison with the chicken H5 gene demonstrates that the 3' non-translated segment of the polyadenylated H5 mRNA carries two conserved dyad symmetry sequences. The first potential hairpin is located directly after the termination codon of the H5 gene and is highly conserved, whereas the second stem and loop structure maps shortly upstream of the polyadenylation site and shows a homology block at the central part of this inverted DNA repeat.