Small nucleolar RNA U6-53/MBII-28

In molecular biology, Small nucleolar RNA U6-53 (also known as MBII-28) is a non-coding RNA (ncRNA) molecule which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA.

snoRNA U6-53 belongs to the C/D box class of snoRNAs which contain the conserved sequence motifs known as the C box (UGAUGA) and the D box (CUGA). Most of the members of the box C/D family function in directing site-specific 2'-O-methylation of substrate RNAs.

This snoRNA possesses sequence complementarity to U6 spliceosomal RNA and is likely to direct its 2'-O-methylation.