Small nucleolar RNA Z195/SNORD33 family

In molecular biology, Small nucleolar RNA Z195/SNORD33 (also known as U33) 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.

Small nucleolar RNA Z195/SNORD33/SNORD32 family
Predicted secondary structure and sequence conservation of SNORD33
Identifiers
Symbol	SNORD33
Alt. Symbols	snoZ195
Rfam	RF00133
Other data
RNA type	Gene; snRNA; snoRNA; C/D-box
Domain(s)	Eukaryota
GO	GO:0006396 GO:0005730
SO	SO:0000593
PDB structures	PDBe

snoRNA Z195/SNORD33 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.^[1]

Plant snoRNA Z195 was identified in a screen of Arabidopsis thaliana.^[2]

An experiment that looked at 22 different non-small-cell lung cancer tissues found that SNORD33, SNORD66 and SNORD76 were over-expressed relative to matched noncancerous lung tissues.^[3]