FIG. 1.

Specificity and sensitivity of the anti-GerQ antiserum. The samples in the various lanes are as follows: A, purified His₁₀-GerQ (30 ng); B, extract from 2 × 10⁴ E. coli cells of strain KE96 carrying plasmid pKE95 (pET11a-gerQ) induced to overexpress the untagged GerQ; C, extract from 2 × 10⁴ cells of strain PS2602 carrying the empty vector pET11a. The cell extracts were prepared in parallel as described in Materials and Methods. Samples were run on SDS-PAGE (10% polyacrylamide), proteins were transferred to an Immobilon-P membrane, and GerQ was detected as described in Materials and Methods. The numbered bars to the right of the figure indicate the migration positions of mass markers in kilodaltons. The band at the position of the asterisk is the His₁₀-GerQ product, and the band at the position of the dot is the untagged GerQ. Note that the anti-GerQ antiserum fails to cross-react with any E. coli host proteins.