Protein with lectin and protease activity involved in the establishment of trypanosome infections in tsetse flies. Binds D-glucosamine and agglutinates bloodstream-form trypanosomes and rabbit red blood cells. Capable of inducing transformation of bloodstream-form trypanosomes into procyclic (midgut) forms in vitro. Expressed in the midgut. By blood meal. Belongs to the peptidase S1 family.