SscA interacts with the translocon protein SseC. (A) Wild type Salmonella (left panels) and a strain carrying a plasmid expressing SscA-FLAG (right panels) were grown in LPM minimal medium, lysed and subjected to immunoprecipitation with anti-FLAG antibody. Immunoprecipated proteins were probed by Western blot with anti-SseC antiserum and anti-FLAG antibody. (B) A reciprocal immunoprecipitation to that shown in part A was performed with a strain expressing SscA-His6 and a strain expressing both SscA-His6 and SseC-FLAG as indicated. SseC-FLAG was immunoprecipitated and proteins were blotted using anti-His and anti-FLAG antibodies. (C) SscA-FLAG does not immunoprecipitate the SseB or SseD translocon proteins. The specificity of the SscA-SseC interaction was tested by probing SscA-FLAG immunoprecipitates with antibodies raised against SseD and SseB, neither of which was detectable in the final eluted protein fraction. Each immunoprecipitation experiment was repeated three times with similar results.