Figure 5.

Schematic model of CyaA action on target membrane. After binding to CD11b/CD18 on myeloid cells [17,18], CyaA penetrates the cytoplasmic membrane and employs two distinct conformers to exert its multiple activities [68]. One would be the translocation precursor that would account for delivery of the invasive AC domain across the lipid bilayer [69] and provoke a concomitant influx of calcium ions into cell cytosol [28]. The other conformer would form a pore precursor that would oligomerize into CyaA pores [11,66,68], provoking potassium efflux from target cells [34]. Not drawn to scale.