Figure 4. mett‐10 is required for effective production of NMD isoforms from the sams genes in␣vivo .

• A
  Nucleotide sequence alignment of putative stem‐loop structures in the C. elegans sams‐3, sams‐4, and sams‐5 genes together with six hairpin structures in 3′UTR of the human MAT2A gene. Conserved residues are shaded in black. Loop, transition, and stem regions of the MAT2A hairpins (Doxtader et␣al, 2018) are boxed in magenta, green, and gray, respectively. An arrowhead indicates adenine bases in the MAT2A hairpins that are specifically modified into m⁶A by METTL16 in␣vitro (Shima et␣al, 2017).
• B
  Schematic representation of the predicted hairpin structures in sams‐3/sams‐4 (left) and sams‐5 (right) pre‐mRNAs. The boundaries between intron 2 and exon 3 are indicated. Arrowheads indicate the m⁶A modification sites.
• C
  Alternative splicing of sams‐3, sams‐4, and sams‐5 in smg‐2 (yb979) and smg‐2 (yb979); mett‐10 (ok2204) mutants. Synchronized L1 larvae of each strain were incubated in S‐complete medium alone (lanes 1 and 3) or with OP50 (lanes 2 and 4) for 3 h at 20°C, and the splicing patterns were analyzed and presented as in Fig 2B.