Small nucleolar RNA SNORD15 C/D family function in directing site-specific 2'-O-methylation of substrate RNAs. U15 is predicted to guide the 2'O-ribose methylation of 28S ribosomal RNA (rRNA) residue A3764. In humans there are two closely related copies of the U15 snoRNA (called SNORD15A and SNORD15B). They are both encoded in the introns of the ribosomal protein S3. In "Xenopus laevis" it is located within the introns of ribosomal protein S1 snoR75 from "Arabidopsis thaliana" and homologues in rice "Oryza sativa" and other plants are alternatively known as U15, and, despite a significantly shorter sequence length, appear to be related. Small nucleolar RNA SNORD15 SNORD15
Helitron (biology) Helitron (biology) Helitrons are one of the three groups of eukaryotic class 2 transposable elements (TEs) so far described. They are the eukaryotic rolling-circle transposable elements which are hypothesized to transpose by a rolling circle replication mechanism via a single-stranded DNA intermediate. They were first discovered in plants ("Arabidopsis thaliana" and "Oryza sativa") and in the nematode "Caenorhabditis elegans", and now they have been identified in a diverse range of species, from protists to mammals. Helitrons make up a substantial fraction of many genomes where non-autonomous elements frequently outnumber the putative autonomous partner. Helitrons seem to have a major role