Figure 5. The PfPKA phosphorylated residue S610 is required for efficient merozoite invasion.

(A) Schematic representation of the ectopically expressed TY1-tagged AMA1. Signal peptide (blue), prosequence (PS), ectodomains I, II & III, transmembrane domain (grey), cytoplasmic tail (C) and TY1-tag (red) are indicated. (B) Mutations introduced into the cytoplasmic tail of W2mef-derived AMA1 are shown in red colour. (C) Expression of W2mef-derived AMA1-TY1 and native 3D7 AMA1 detected by Western Blot analysis using an anti-TY1 and anti-AMA1 (1F9) antibody, respectively (C, left panel). Whereas no AMA1-TY1 protein can be detected in 3D7 wild type parasites, a double band corresponding to AMA1₈₃-TY1 and processed AMA1₆₆-TY1 can be detected in AMA1-TY1-expressing parasites. (C, right panel) The endogenous 3D7 AMA1 is recognised by the anti-AMA1-1F9 antibody and shows identical proteolytic forms of AMA1 (AMA1₈₃ and AMA1₆₆). (D) Invasion inhibition assays using AMA1-TY1 expressing parasite strains. Assays were performed in the presence of 100 µg/mL R1 peptide and were performed in triplicate in three independent experiments. Error bars correspond to standard deviation. 3D7 and AMA1-WT-TY1 served as control.