Fig. 3.

Interaction between Ub and the JD as assessed by NMR chemical shift perturbation. (A) Chemical shift perturbation of the JD upon interaction with Ub. Ribbons are colored according to whether corresponding backbone nuclei experienced primarily chemical shift changes (from gray to yellow) or loss of signal intensity (from yellow to orange) as detailed in Materials and Methods. The position of the catalytic site is marked by dashed-line circle. C, C terminus; N, N terminus. (B) Chemical shift perturbation of Ub upon interaction with the JD of ataxin-3. The color code is the same as in A. The ribbon diagram was generated from deposited Ub structure coordinates (Protein Data Bank ID code 1UBQ).