REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
TRIM25 polyclonal rabbit	Thermo Scientific	cat # 12573-1-AP; RRID: AB_2209732
ISG15 monoclonal rabbit (7H29L24)	Thermo Scientific	cat # 703131; RRID: AB_2784562
PARP13 (ZC3HAV1) polyclonal rabbit	ProteinTech	cat # 16820-1-AP; RRID: AB_2728733
PARP13 (ZC3HAV1) polyclonal rabbit	Thermo Scientific	cat #PA5-31650; RRID: AB_2549123
β-Actin monoclonal mouse (clone AC-15)	Sigma Aldrich	cat # A5441; RRID: AB_476744
GFP mouse IgG1κ (clones 7.1 and 13.1)	Roche	cat # 11814460001; RRID: AB_390913
OAS2 polyclonal rabbit	ProteinTech	cat # 19279-1-AP; RRID: AB_10642832
Critical commercial assays
Dual-Luciferase Reporter Assay System	Promega	cat #E1910
PowerUp SYBR Green master mix	Thermo Fisher	cat # A25742
SuperScriptTM IV VILO Master Mix	Invitrogen	cat # 11754050
TRIzol reagent	Invitrogen	cat # 15596026
100x Halt protease inhibitor cocktail	Thermo Fisher	cat # 78429
SUPERase-In RNase inhibitor	Thermo Fisher	cat # AM2694
4x NuPAGE LDS sample buffer	Thermo Fisher	cat # NP0007
20x NuPAGE MOPS SDS running buffer	Thermo Fisher	cat # NP0001
20x NuPAGE transfer buffer	Thermo Fisher	cat # NP0006
AmpliScribeTM T7 High Yield Transcription Kit	Lucigen	cat # AS3107
Lipofectamine 2000 Transfection Reagent	Thermo Fisher	cat # 11668500
1X Dulbecco’s Modified Eagle Medium	Gibco	cat # 11995073
fetal bovine serum	Sigma Aldrich	cat #F6765
Opti-MEM(R) I Reduced-Serum Medium (1X)	Gibco	cat # 31985062
Deposited data
TRIM25 CLIP-seq	Choudhury et al. 28	GEO: GSE104949
APEX-RIP	Kaewsapsak et al. 35	GEO: GSE106493
PARP13 eCLIP and RNA-seq data	This publication	GEO: GSE215251
Experimental models: Cell lines
HEK 293T	ATCC	cat # CRL-3216; RRID: CVCL_0063
PARP13 KO HEK 293T	Hayakawa et al. 2	clone 32, c.1023_1047del25insGTT, c.1027_1046del20, c.1031_1032insATCCA and c.1033_1034insCAATC
Oligonucleotides
ssRNA	IDT	CACUUUCACUUCUCCCUUUUAGUUUCC
3p-RNA	IDT	TAATACGACTCACTATAGGAAACTAAAAGGG AGAAGTGAAAGTG and CACTTTCACTTCTCC CTTTTAGTTTCCTATAGTGAGTCGTATTA
siPARP13	Thermo Fisher	siRNA ID # HSS125638, cat # 1299001
Recombinant DNA
EGFP-PARP13.1	This paper
EGFP-PARP13.2	This paper
EGFP-PARP13.2(Q)	This paper
dual luciferase PARP13.1 3′UTR	This paper
dual luciferase PARP13.2 3′UTR	This paper
Software and algorithms
nearBynding	Busa et al. 39	https://bioconductor.org/packages/nearBynding/; https://github.com/vbusa1/nearBynding
HOMER	Heinz et al. 34	http://homer.ucsd.edu/homer/motif/
GOrilla	Eden et al. 48	http://cbl-gorilla.cs.technion.ac.il/
Revigo	Supek et al. 49	http://revigo.irb.hr/
EMBOSS: compseq	Rice et al. 50	http://emboss.sourceforge.net/apps/cvs/emboss/apps/compseq.html
CLIPper	Lovci et al. 51	https://github.com/YeoLab/clipper/releases/tag/1.0