Small noncoding RNAs are typically only ~18–40 nucleotides in length, but their effects on cellular processes are profound. Small RNAs have been shown to play critical roles in developmental timing, cell fate, tumor progression, and neurogenesis.
Animals, plants, and fungi contain several distinct classes of small RNAs, including:
- microRNA (miRNA)
- short interfering RNA (siRNA)
- piwi-interacting RNA (piRNA)
- repeat associated small interfering RNA (rasiRNA)