Fig 1: Irp2 deficiency reduces the ms2t6A modification in tRNALysUUU causing misreading of lysine codons in proinsulin.a Secondary structure and sequence of tRNALysUUU with anticodon loop modifications 2-methylthio-N6-threonylcarbamoyl adenosine (ms2t6A37), methoxycarbonylmethyl-2-thiouridine (mcm5s2U34) and pseudouridine-39 (?-39). The ms2 group on ms2t6A37 is indicated by a dotted circle. Adapted from Vendeix, et al.68. b Western blot analysis of Cdkal1 in control, sgIrp2.1, and sgIrp2.2 INS-1 cells grown in medium with or without DFO or FAC for 18 h. ß-Actin is a loading control. Asterisk, nonspecific band. c Western blot analysis of Irp2, Cdkal1, Pcsk1, and CgA in islets isolated from 6-month old WT and Irp2-/- mice. Gapdh is a loading control for Irp2, Cdkal1 and Pcsk1 and ß-actin is a loading control for CgA (n = 3 mice per genotype). d–e LC-MS analysis of ms2t6A (d) and t6A (e) modifications in control, sgIrp2.1, and sgIrp2.2 INS-1 cells grown in medium with or without supplemental FAC for 18 h (n = 3 independent biological experiments). f Relative incorporation of 14C-lysine versus 3H-leucine in proinsulin immunoprecipitated from control, sgIrp2.1, and sgIrp2.2 INS-1 cells grown in medium with or without supplemental FAC (n = 3 independent biological experiments). Data in d, e are expressed as means ± s.e.m., unpaired two-tailed Student’s t test, *p < 0.05, **p < 0.01 relative to control INS-1 cells; data in f are expressed as means ± s.e.m., compared by one-way ANOVA with Tukey’s multiple comparison test, *p < 0.05, **p < 0.01. g Model of Irp2 regulation of proinsulin processing and insulin secretion in ß cells. Source data are provided as a Source Data file.