Acknowledgements: We would like to thank Prof. Gavin J. Wright for his help during the construct designing for expression vectors and for providing the HEK 293E cell line for protein expression. Dr. Robert W. Moon for providing the CRISPR Cas9 plasmid and Plasmodium knowlesi A1.H1 line. Dr. Reiner Schulte, Gabriela Grondys-Kotarba and Chiara Cossetti of the CIMR Flow Cytometry facility for providing required training and assistance during the flow cytometry experiments. We also like to convey our thanks to Matthew Gratian and Mark Bowen for providing training and data acquisition in LSM880 confocal microscope with Airyscan setting. We are grateful to Alison Kemp for her guidance to use the CRISPR Cas9 system. Ellen Knuepfer for the kind donation of Rat anti-PkMSP1-19 serum. We thank Stephen Graham for help with crystallographic model building. We acknowledge Diamond Light Source for time on beamline I04 under proposal MX21426. This work was funded by the National Institutes of Health (R01AI137154) and the Wellcome Trust (220266/Z/20/Z). J.E.D. and S.J.M. are supported by a Wellcome Trust Senior Research Fellowship (219447/Z/19/Z) awarded to J.E.D. As this research was funded in part by the Wellcome Trust, for the purpose of open access, the author has applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission.