Dnop56, a Drosophila gene homologous to the yeast nucleolar NOP56 gene

Small nucleolar RNAs (snoRNAs) are trans-acting factors involved in maturat ion of rRNA and have been classified into Box C/D and Box H/ACA families. M ost of the snoRNAs occur as ribonucleoprotein complexes with snoRNA-associa ted proteins (snoRNPs). All Box C/D snoRNAs in yeast form complexes with No p1p, Nop56p and Nop58p. Similarly, it has been reported that Box H/ACA-cont aining snoRNAs form complexes with yeast Gar1p. Nop56p and Nop58p homologs have been described in several species. Here we report the isolation and mo lecular characterization of the Dnop56 genes from D. melanogaster and D. su bobscura which show a very similar structure. Drosophila Nop56p proteins co ntain lysine-rich regions at their carboxy-terminus, and show a high degree of similarity to other Nop56p proteins from different organisms. Phylogene tic relationships among these proteins and other snoRNPs have been establis hed.