Immunoblot of wild-type and mutant OppA proteins. Total cell lysates were resolved by SDS–10% polyacrylamide gel electrophoresis, transferred to a polyvinylidene difluoride membrane, and probed with antibodies raised against OppA. Lysates of IM15, AMP2, AMP2/pAMP31, AMP2/pAMP31(K349Q), AMP2/pAMP31(N422H), AMP2/pAMP31(A423H), AMP2/pAMP31(D471R), AMP2/pAMP31(A477D), and IM15 are indicated; 20 μg of protein was present in each lane.