Forms a pore with IpaB, which is inserted into host cell membrane through the Mxi/Spa apparatus, during cell contact. This pore probably allows the translocation of IpaA. The C-terminus of IpaC could be involved in actin polymerization that leads to the cell extension formation and its N-terminus could be involved in the conversion of filopodial extensions into lamellipodial extension. Most extensions results from Cdc42 activation by IpaC whereas the lamellipodial extensions result from the Rac activation by Cdc42.