Engelsk definition
A class of small RNAs that are 24–31 nucleotides in length. They associate with the PIWI SUBFAMILY OF ARGONAUTE PROTEINS to form effector complexes known as piRNA-induced silencing complexes, which repress transposons via transcriptional or posttranscriptional mechanisms and maintain germline genome integrity. In addition to their role in transposon silencing, piRNAs in diverse organisms function in the regulation of cellular genes.