Detection of truncated PilQ complexes. Total membranes (50 μg of protein) of the T. thermophilus HB27 wild type and membranes of pilQwt, ΔpilQ::bleo, N1Δβ1β2, N1β3αβ4, ΔN1, ΔN2, ΔN3, ΔN4, and ΔN5 mutants were separated by 3–12% SDS-PAGE and subjected to Western blotting analysis using polyclonal PilQ antibodies (1:10,000 dilution). The full-length PilQ monomers are indicated by arrows.