U31 is encoded within the U22 snoRNA host gene (UHG) in mammals and is thought to act as a 2'-O-ribose methylation guide for ribosomal RNA.
Within the context of mammalian cells, U31 is embedded in the U22 small nucleolar RNA host gene (UHG) and acts as a directive for the modification of ribosomal RNA through 2'-O-ribose methylation.