Radiolabeled nucleotides

Oligonucleotides were obtained from TsingKe (Beijing, China). DNase I, restriction endonucleases, E. coli inorganic pyrophosphatase, E. coli Poly(A) Polymerase, RNA 5′ Pyrophosphohydrolase (RppH), T4 DNA ligase, NTPs, dNTPs, and RNA purification kits were from New England BioLabs (Ipswich, MA, United States). RNase inhibitor was from Thermo Fisher Scientific (Waltham, MA, United States). PrimeSTAR Max DNA Polymerase and Premix Taq DNA Polymerase, SMARTScribe and ProtoScript II Reverse Transcriptase are were from TAKARA (Shiga, Japan). DNA purification kit was from Axygen (Union City, CA, United States). Ni-NTA resin was from Qiagen (Hilden, Germany). Preparative Superdex S200 for gel filtration was from GE Healthcare (Chicago, IL, United States). Radiolabeled nucleotides were from PerkinElmer (Waltham, MA, United States). 2′-F-dNTPs were from TriLink (San Diego, CA, United States).

Restriction enzymes were from New England Biolabs; Nytran membranes from Schleicher & Schuell; QuickChange Mutagenesis Kit from Stratagene; Random Primed DNA Labeling Kit from Roche Applied Science; and radiolabeled nucleotides from Perkin-Elmer Life Science. LB (Luria broth) contained bacto tryptone (10 g/L), yeast extract (5 g/L), and sodium chloride (10 g/L).