Identification of PfGARP by phage display screens and RBC-binding assay. (A) Schematic representation of PfGARP segments identified by phage display screens. PfGARP-L (blue) and PfGARP-S (purple) are 2 overlapping sequences obtained from independent phage display P falciparum screens using human RBCs as bait. PfGARP-M (red and green) is a codon-optimized stable segment. PfGARP-M1 (red) and PfGARP-M2 (green) are nonoverlapping segments of PfGARP-M protein. (B) A 75-AA acid sequence of PfGARP-M (3D7) was obtained from PlasmoDB site.⁷⁶  PfGARP-M1 (red) consists of 9 repeats, and PfGARP-M2 (green) consists of 5 repeats. (C) Expression, purification, and RBC binding of TRX-PfGARP recombinant proteins. All PfGARP-S, PfGARP-M, and PfGARP-L proteins bound to RBCs. PfGARP-M showed the least degradation. (D) Expression, purification, and RBC binding of TRX–PfGARP-M1 and PfGARP-M2 proteins. PfGARP-M and PfGARP-M2 bound to RBCs but not PfGARP-M1. TRX served as a negative control. All protein concentrations were normalized at 1.0 μM, and NaCl (1.5 M) was used to elute RBC-bound proteins. Mouse monoclonal anti-TRX antibody was used to detect protein-binding signals.