21U-RNA

{{technical|date=May 2020}}

21U-RNAs are microRNA molecules 21 nucleotides long found in nematodes such as Caenorhabditis elegans. They begin with a 5' uridine. The remaining 20 nucleotides are diverse. They are modified at their 3′-terminal ribose.{{cite journal | vauthors = Ruby JG, Jan C, Player C, Axtell MJ, Lee W, Nusbaum C, Ge H, Bartel DP | title = Large-scale sequencing reveals 21U-RNAs and additional microRNAs and endogenous siRNAs in C. elegans | journal = Cell | volume = 127 | issue = 6 | pages = 1193–1207 | date = December 2006 | pmid = 17174894 | doi = 10.1016/j.cell.2006.10.040 | s2cid = 16838469 | doi-access = free }} See Piwi-interacting RNA.