Fig. 1. CPA-seq.

a The workflow of sRNA library preparation for CPA-seq. Purified small RNAs are incubated in deacylation buffer to remove 3′-aminoacyl (3′-aa), treated with Cap-Clip to remove 5′ m⁷G and m³G caps, then treated with T4 PNK to convert 5′-OH to 5′-P, and to convert 3′-P and 3′-cP to 3′-OH, followed by treatment with a mix of AlkB and AlkB(D135S) to remove methylations in m¹G, m³C, and m¹A. The pretreated small RNAs were ligated with 3′ and 5′ adapters, reverse transcribed by TGIRT-III, and then PCR amplified for sequencing. b Northern blotting of RNA samples from HEK293T with/without treatment of deacylation buffer. c Cap-Clip treated synthetic 5′-m⁷G-RNA (31 nt) was ligated with a 5′-adapter (26 nt). d T4 PNK-treated synthetic 5′-OH RNA (27 nt) was ligated with a 5′-adapter (26 nt). e T4 PNK-treated synthetic 3′-P RNA (27 nt) was ligated with 3′-adapter (29 nt). f LC-MS/MS analysis showed that sequential treatments with deacylation buffer, Cap-Clip, T4 PNK, and AlkB mix (CPA) efficiently removed methylations in m¹G, m³C, and m¹A of small RNAs extracted from HEK293T cells (n = 3).