Figure 3. Impaired protein assembly of the 26 S proteasome in IEX-1-expressing HEK-293 cells.

Cellular lysates from Tet-293-mock and Tet-293-IEX-1 cells (clone a3) treated with tetracycline (16 h, 1 μM) were submitted to 10–30% (w/v) sucrose-density-gradient ultracentrifugation (28 000 rev./min; 30 h; SW28 rotor) and fractions thereof were analysed by Western blot detecting the proteasomal proteins α6/C2 and S5a, the maturation factor hUMP1 or, as the control, Hsp90. A representative result from three independent experiments is shown. The positions of sedimented proteasomal subcomplexes and precursor complexes (p.c.) are indicated.