| transfer RNA |
tRNA |
73–93 nt |
Transfers amino acids to the ribosome during translation of mRNA to protein (Hoagland et al., 1958) |
| ribosomal RNA |
rRNA |
120–5035 nt |
Translation of mRNA to protein (Watson, 1963) |
| small nuclear RNA |
snRNA |
90–220 nt |
RNA splicing (Lerner et al., 1980) |
| small nucleolar RNA |
snoRNA |
C/D box-70–120 nt
H/ACA-100–200 nt |
Guide the modification and maturation of other ncRNAs (Crouch et al., 1983) |
| long non-coding RNA/long intergenic non-coding RNA |
lncRNA/lincRNA |
>200 nt |
Epigenetic gene regulation (Sleutels et al., 2002) |
| microRNA |
miRNA |
21–22 nt |
Translation inhibition; binds mRNA to block translation (Lee et al., 1993) |
| short/small interfering RNA |
siRNA |
21–25 nt |
Translation inhibition; binds mRNA to signal cleavage (Hamilton and Baulcombe, 1999) |
| endoribonuclease-prepared short interfering RNA |
esiRNA |
20–25 nt |
RNA interference (Yang et al., 2002) |
| repeat-associated small interfering RNA *previous name for piRNAs |
rasiRNA |
24–29 nt |
Silencing of retrotransposons in the germline (Aravin et al., 2003) |
| piwi-interacting RNA |
piRNA |
26–31 nt |
Silencing of retrotransposons in the germline (Brennecke et al., 2007) |
| centromere repeat-associated small interacting RNA |
crasiRNA |
35–42 nt |
Centromere identity and function (Carone et al., 2008) |
| small RNAs derived from snoRNAs |
sdRNA |
17–19, >27 nt |
Gene regulation (Ender et al., 2008) and alternative splicing (Kishore et al., 2010) |
| transcription initiation RNA |
tiRNA |
18 nt |
Unclear; may function in transcription regulation (Taft et al., 2009) |
| splice site RNA |
spliRNA |
17–18 nt |
Unclear; generated from the donor splice site in animal internal exons (Taft et al., 2010) |
| tRNA-derived RNA fragments |
tRFs |
18–22 nt, 30–35 nt |
miRNA-like functions; gene regulation (Lee et al., 2009) |
