Western blotting analysis with 23K antibodies to detect TorA-23K in supernatants of 30-h cultures from S. lividans TK24 (lane 1), S. lividans(pVsiTor23K) (lane 2), S. lividans ΔtatC(pVsiTor23K) (lane 3), and S. lividans ΔtatC(pVsiTor23K)(pSETtatC) (lane 4) grown in NB medium. In each lane, the amount of supernatant corresponding to 3 mg of dry weight was loaded. A 23K-specific immunoreactive band is present in wild-type S. lividans carrying pVsiTor23K, absent in S. lividans ΔtatC(pVsiTor23K), but restored in S. lividans ΔtatC(pVsiTor23K)(pSETtatC).