A subpopulation of 4.1R is found at the PVM in Plasmodium falciparum- infected erythrocytes. (A) Rabbit polyclonal antibodies raised against the FERM domain of 4.1R recognize a major band at the size of full-length 4.1R (80kDa) in both uninfected (−) and P. falciparum-infected (Pf) erythrocytes. Additional bands are either proteolytic cleavage products or alternatively spliced products of 4.1R as the same bands were recognized in both uninfected and P. falciparum- infected erythrocytes. (B, C) Immunofluorescence microscopy of air-dried smears of 3D7 P. falciparum-infected erythrocytes probed with rabbit anti-4.1R (green). 4.1R consistently localizes near the erythrocyte plasma membrane (black arrows), but in early (B) and late (C) trophozoite-stage parasites, a subpopulation of 4.1R is found in close apposition to the parasite, as detected by DAPI staining (blue).