Extended Data Fig. 9 ∣. Measurement of ¹H_M-Γ₂ PRE rates in the 89 kDa MR1/TAPBPR complex.

a, Melting temperature (T_m, °C) of TAPBPR^WT (black) and TAPBPR^L30C-MTSL (grey) obtained from differential scanning fluorimetry experiments. Data are mean ± SD for n = 3 technical replicates. b, 2D ¹H-¹³C methyl HMQC spectra of 100 μM Ac-6-FP/ILV^proS labeled hpMR1/bβ₂m in complex with TAPBPR^L30C-MTSL in the oxidized (paramagnetic, blue) or reduced (diamagnetic, red) state recorded at a ¹H field of 600 MHz at 25 °C. Dotted boxes highlight a subset of the methyl resonances affected upon reduction of TAPBPR^L30C-MTSL by ascorbic acid. c, Position of representative ILV^proS methyl groups analyzed in panel d shown on the RosettaCM model of hpMR1 (PDB template 4PJ5, TCR removed). d, TAPBPR^L30C-MTSL was complexed with Ac-6-FP/ILV^proS hpMR1/bβ₂m and ¹H_M R₂ values were measured for oxidized (paramagnetic, blue) and reduced (diamagnetic, red) samples by recording a series of 2D methyl ¹H-¹³C HMQC spectra and analyzing the NMR peak intensity as a function of a varied transverse relaxation delay (0, 6, 24, 36, 50 and 68 msec). The decay profiles for selected ¹H methyl groups of L10 δ2, V28 γ2, I96 δ1 and L246 δ2 of hpMR1 are shown. A summary of all measured ¹H_M-Γ₂ PRE rates is shown in Supplementary Table 5.