U87 RNA, a novel C/D box small nucleolar RNA from mammalian cells.

A novel 72 nt small nucleolar RNA (snoRNA) called U87 was found in rat liver cells. This RNA possesses the features of C/D box snoRNA family: boxes C, D', C', D, and 11 nt antisense element complementary to 28S ribosomal RNA (rRNA). The vast majority of C/D box snoRNAs direct site-specific 2'-O-ribose methylation of rRNAs. U87 RNA is suggested to be involved in 2'-O-methylation of a G(3468) residue in 28S rRNA. U87 RNA was detected in different mammalian species with slight length variability. Rat and mouse U87 RNA gene was characterized. Unlike the majority of C/D box snoRNAs U87 RNA lacks the terminal stem required for snoRNA processing. However, U87 gene is flanked by 7 bp inverted repeats potentially able to form a terminal stem in U87 RNA precursor.