Subcellular localization of B. burgdorferi proteins DnaK, OspA, OppA4, HflC and FtsH analyzed by SDS-PAGE and Western blot. A. DnaK, OspA and OppA4 antibodies were used to assay the separation of the OM and the IM fractions. B. HflC and FtsH proteins were associated exclusively with the IM fraction, supporting their association with the inner membrane. OM: outer membrane; IM: Inner membrane. Controls using secondary antibodies alone were non-reactive (not shown).