Fig. 1.

Interaction of human REV1 (932–1039) with ubiquitin. (a) Prediction of α-helical (red) and β-sheet (blue) regions in apo REV1 (top) and in REV1 titrated with threefold molar excess ubiquitin (bottom) based on TALOS+ analysis of Cα, Cβ, C′, HN and N NMR chemical shifts [43]. The UBM1 and UBM2 regions are shown in orange. (b) Chemical shift perturbations in the ¹H–¹⁵N HSQC spectrum of ¹⁵N-labeled REV1 (1 mM concentration) caused by addition of threefold molar excess of unlabeled ubiquitin. The normalized chemical shift changes Δδ in parts per million (ppm) for the ¹H–¹⁵N correlation signals are defined as $\Delta \delta =\sqrt{{\left(\Delta {\delta }_{\mathrm{H}}\right)}^2+{(\Delta {\delta }_{\mathrm{N}}∕5)}^2}$. (c) Overlay of the ¹H–15^N HSQC spectra of ¹⁵N-labeled REV1 at 0.5 mM concentration before and after addition of threefold molar excess of unlabeled ubiquitin. (d) Overlay of the ¹H–¹⁵N HSQC spectra of ¹⁵N-labeled ubiquitin at 0.3 mM concentration before and after addition of 5-fold molar excess of unlabeled REV1.