Homo sapiens C/D box snoRNA mgU6-77. This snoRNA is the human orthologue of the mouse snoRNA mgU6-77 characterized by a bioinformatics search of anti-sense elements followed by CTGA in the mouse genome (Tykowski et al., 1998). It is predicted to guide the 2'O-ribose methylation of both U6 snRNA C77 and 28S rRNA C3787. In Xenopus oocytes, mgU6-47 is required for the methylation of the corresponding nucleotides in U6 snRNA and 28S rRNA. mgU6-77 shares the same host gene with the H/ACA box snoRNAs U67 and ACA48 (EIF4A1).