Z3, a novel antisense snoRNA from Saccharomyces cerevisiae

Small nuclrular RNA (snoRNA) is one of the most important elements participating in eukaryotic ribosomal biogenesis. The present report describes the results of the identification of a novel snoRNA, Z3, from yeast S.cerevisiae. Z3 snoRNA is 106 nts in length. It contains box C, D elements and a 13 nt complementarity to 25S rRNA. Thia antisense segment, together with the downstream box D, guides a 2′-O-ribose methylation of cytidine acid at position 2956th in yeaat 25 S rRNA. Z3 snoRNA, encoded by an independent transcribed gene on the chromosomeXI of yeast, poseses the same functional elements responsible for the rRNA methylation site as that of the intron-encoded U35 snoRNA of vertebrate.