Domain organization of recombinant MSP1. (A) MSP1 is grouped into 17 blocks classified as conserved, semiconserved, or variable. The diagram shows 4 subunits of MSP1 following the action of subtilisin-1.²⁶  Two independent overlapping phage clones of MSP1 are indicated. Clone 1, identified in the screen using purified glycophorins, consists of amino acids 204 to 250, whereas clone 2, identified in the screen against neuraminidase-treated RBCs, encodes amino acids 240 to 279. The MSP1₁₂ construct incorporates both clones 1 and 2. The respective locations of MSP1_83A, MSP1_83B, and MSP1₁₉ are also annotated. (B) Coomassie-stained sodium dodecyl sulfate–polyacrylamide gel electrophoresis of MSP1 fusion proteins includes MSP1₅, containing amino acids 204 to 250 from phage clone 1. MSP1₁₂ (amino acids 194-296) expresses a relatively stable protein encompassing both phage clones. MSP1_83A and MSP1_83B cover the entire 83-kDa N-terminal subunit of MSP1.