FIG. 3.

InvB specifically binds SopE. Whole-cell lysates of wild-type Salmonella serovar Typhimurium or its isogenic ΔsopE mutant were separated by SDS-PAGE and transferred to a PVDF membrane. The blot was treated with a soluble lysate of E. coli expressing M45 epitope-tagged InvB, and the bound InvB-M45 was detected with a monoclonal antibody directed against M45 as previously described (11). Notice that in addition to SopE, InvB binds to a high-molecular-mass band, which has been tentatively identified as SipA, consistent with a previous report (2). More experiments would be required for confirmation of the identity of this protein.