Primary and secondary structure of S.8S rRNA from the silkgbnd ofBombyx mori

Abstract
Nucleotide sequence of 5.8S rRNA of the silkworm, Bombyx mori has been determined by gel sequencing methods. The 5.8S rRNA was the longest so far reported, with the 5'-terminal sequence several nucleotides longer than those of the other organisms. Upon constructing the secondary structure in accordance with the ‘burp gun’ model (12), the Bombyx 5.8S rRNA formed a wide-open ‘muzzle’ due to several unpaired bases at the ends. The overall structure also appeared less stable with less G pairs and more unpaired bases than that of the HeLa 5.8S rRNA. These structural features may be essential for those 5.8S rRNAs which interect with 28S rRNAs containing the hidden break to form a stable complex.