Figure 3.

RNA binding activity of VCR facilitates U6 snRNA methylation. (A) The arginine-rich region (RRR: amino acid residues 382–388) resides between β3 and β4 (left). Conservation analysis of the VCR of METTL16 (right). Conserved and non-conserved residues are colored purple and cyan, respectively (Supplementary Figure S3). (B) Methylation of U6 snRNA by METTL16 variants. Relative activities of METTL16 variants. The activity of METTL_FL under the conditions described in Figure 2E was taken as 1.0. ΔRRR: METTL16 lacking RRR in the VCR. (C) Steady-state kinetics of m⁶A modification of U6 snRNA by METTL16_FL and ΔRRR. (D) Gel shift of U6 snRNA by wild-type VCR (VCR_wt) and its variant lacking RRR, VCR_ΔRRR (0–2.0 μM) (Supplementary Figure S1C). Bars in the graphs in (B)–(D) are standard deviations (SD) of three independent experiments.