Subcellular localization of IglA. Anti-IglA was used to probe Western immunoblot of subcellular fractions of F. novicida. The sarkosyl insoluble fraction represents an enrichment of outer membrane protein and the sarkosyl soluble fraction contains largely inner membrane protein. Samples were prepared as outlined in Methods and normalized to 10 μg protein per lane before separation on a 12% SDS-PAGE gel. Results are representative of three independent experiments.