Fig. 2. OTULIN deficiency causes proteasome dysfunction.

(A) The Lys⁴⁸ ubiquitination (Ub) levels in patients’ and one healthy control’s fibroblasts. (B) Proteasome chymotryptic, tryptic, and caspase-like activity in fibroblasts from three patients and two healthy controls. (C) Proteasome chymotryptic, tryptic, and caspase-like activity in PBMCs from two patients and six healthy controls. P3 was sampled twice. (D to F) Native gel analysis of the proteasome assembly in fibroblasts from three patients and three healthy controls. The assembly of different parts of the proteasome was illustrated using antibodies of different subunits correspondingly. CP, core particle; RP, regulatory particle. (G) Native gel analysis of the proteasome assembly in PBMCs from the patient P3 and four healthy controls. (H) Western blots analysis of linear ubiquitination levels on purified proteasome from patient P1’s and one healthy control’s fibroblasts. Data in (B) and (C) are shown as means ± SEM from four repeated technical analyses. P values were determined by unpaired two-tailed t test. **P < 0.01; ***P < 0.001; ****P < 0.0001.