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

Small nucleolar RNAs (snoRNAs) are trans-acting factors involved in maturation of rRNA and have been classified into Box C/D and Box H/ACA families. Most of the snoRNAs occur as ribonucleoprotein complexes with snoRNA-associated proteins (snoRNPs). All Box C/D snoRNAs in yeast form complexes with Nop1p, Nop56p and Nop58p. Similarly, it has been reported that Box H/ACA-containing snoRNAs form complexes with yeast Gar1p. Nop56p and Nop58p homologs have been described in several species. Here we report the isolation and molecular characterization of the Dnop56 genes from D. melanogaster and D. subobscura which show a very similar structure. Drosophila Nop56p proteins contain lysine-rich regions at their carboxy-terminus, and show a high degree of similarity to other Nop56p proteins from different organisms. Phylogenetic relationships among these proteins and other snoRNPs have been established.