Co-immunoprecipitation of P. brasiliensis proteins putatively interacting with Pb SP. Pb SP and the proteins found interacting with this protease in the two-hybrid assay were in vitro synthesized and labeled with 35S methionine. The translated serine protease fused to c-myc epitope (c-myc-SP) and the translated proteins fused to hemaglutinin epitope (HA-Prey) were mixed and the mixture was incubated with protein A agarose beads and the monoclonal antibody anti-c-myc. The proteins were separated by SDS-PAGE. The gel was fixed, dried under vacuum and autoradiography was obtained. 1: Peptidyl prolyl cis-trans isomerase; 3:Calnexin; 5: HSP70; 7: Periodic tryptophan protein (PWP2). Negative controls for each reaction were performed and are shown in the lanes 2, 4, 6 and 8, respectively.