FIG. 2.

SDS-PAGE of the authentic and heterologously produced M. thermophila 20S proteasome and individual α or β subunits. Lanes: 1, 20S proteasome produced in E. coli; 2, α subunit and β prosubunit independently produced in E. coli, combined in vitro, and incubated for 90 min at 37°C; 3, β prosubunit independently produced in E. coli; 4, α subunit independently produced in E. coli; 5, authentic 20S proteasome purified from M. thermophila. Proteins were stained with Coomassie blue R-250. Molecular size standards are indicated on the right.