Figure 3.

m⁶A can be added to exons before splicing. (A) Compared with input reads, m⁶A immunoprecipitation reads were enriched for pre-mRNA reads containing both intron and m⁶A-containing exon sequences (left) but depleted for exon–intron junction sequence fragments lacking m⁶A (right). (***) P < 10⁻¹⁰⁰, Fisher's exact test. (B) An example of an internal exon in the PRR5 gene. “m⁶A-CLIP site” shows a precise m⁶A site (black box) identified by m⁶A-CLIP. “IP reads” lists the cDNA reads of RNA fragments that were precipitated by m⁶A-specific antibody and contain both the m⁶A site and the unspliced intronic region. This m⁶A site is near a 3′ splice site. (C) An internal exon in the TBX3 gene; this m⁶A site is near a 5′ splice site. More examples are in Supplemental Figure 5.