Fig. 6 ∣. TAPBPR influences ligand residence times in the MR1 groove.

a, Chemical structure of in-house synthesized ¹⁹F-DCF. b, Structural model of ¹⁹F-DCF in the hpMR1 groove (template PDB ID 5U1R, TCR removed). c, 1D ¹⁹F NMR spectra of 10 μM ¹⁹F-DCF titrated with increasing concentrations of empty hpMR1/bβ₂m, recorded using a TCI probe without ¹H decoupling. A plot of NMR signal intensity (I/I₀) as a function of hpMR1 concentration is shown. Data were collected at 25 °C at a ¹H field of 600 MHz. d, 1D ¹⁹F CPMG NMR spectra of 500 μM ¹⁹F-DCF in the presence or absence of 5 μM empty hpMR1-bβ₂m or 5 μM UVirrad HLA-A*02:01–hβ₂m. Also shown are experiments where 10 μM TAPBPR^WT, TAPBPR^TN6 or TAPBPR^ΔG24-R36 were added. The T₂^app values (ms) were estimated from R_int, which represents the change in NMR signal intensity between spectra acquired with short (80 ms CPMG duration, blue spectrum) versus long (240 ms CPMG duration, red spectrum) relaxation filters using a broadband ¹⁹F CPMG experiment collected at 25 °C at a ¹H field of 600 MHz. The NMR signal is split because our NMR probe is not capable of performing simultaneous ¹⁹F detection and decoupling of nearby ¹H spins.