Table 1.

Factors involved in tailing, trimming, and turnover of small RNAs

Factor(s)	Substrates	Activity	Organism(s)	Condition(s)	References
Unknown ubiquitin ligase	Global miRNA decay	Ubiquitylation of AGO proteins	Mus musculus	T cell stimulation	[24]
Vp55	Global miRNA decay	3′-adenylation of miRNAs	Poxvirus	Poxvirus infection	[25]
Wispy	Global miRNA decay	3′-adenylation of miRNAs	Drosophila melanogaster	Maternal-to-zygotic transition	[26]
HEN1 SUPRESSOR1 (HESO1) and UTP:RNA Uridylyltransferase 1 (URT1)	miR-165 miR-166 miR-167 miR-169 miR-170 miR-171 miR-173	3′-uridylation of miRNAs	Arabidopsis thaliana	Degradation of small RNAs lacking 2′-O-methyl group at 3′ end	[40–43]
SMALL RNA DEGRADING NUCLEASE (SDN1–3)	miR-156 miR-159 miR-163 miR-164 miR-165 miR-166 miR-167 miR-172 miR-173 siR1003	Removal of 2′-O-methylated nucleotide at miRNA 3′ end	Arabidopsis thaliana	Degradation of miRNAs loaded into AGO10 (miR-165/166) and other unknown conditions	[44–46]
ZSWIM8/Dora/EBAX-1 ubiquitin ligase	Numerous miRNAs	Ubiquitylation of AGO proteins	Homo sapiens, Mus musculus, Drosophila melanogaster, Caenorhabditis elegans	Extensive complementarity between miRNA and target	[76–84, 91, 92, 96]
HAWAIIAN SKIRT (HWS)	miR-156 miR-159 miR-160 miR-163 miR-164 miR-167 miR-168 miR-319 miR-398	Ubiquitylation of AGO proteins	Arabidopsis thaliana	Association of miRNA with target mimic	[104–106]