title: Subcellular location, phosphorylation and assembly into the motor complex of GAP45 during Plasmodium falciparum schizont development.
abstract: An actomyosin motor complex assembled below the parasite's plasma membrane drives erythrocyte invasion by Plasmodium falciparum merozoites. The complex is comprised of several proteins including myosin (MyoA), myosin tail domain interacting protein (MTIP) and glideosome associated proteins (GAP) 45 and 50, and is anchored on the inner membrane complex (IMC), which underlies the plasmalemma. A ternary complex of MyoA, MTIP and GAP45 is formed that then associates with GAP50. We show that full length GAP45 labelled internally with GFP is assembled into the motor complex and transported to the developing IMC in early schizogony, where it accumulates during intracellular development until merozoite release. We show that GAP45 is phosphorylated by calcium dependent protein kinase 1 (CDPK1), and identify the modified serine residues. Replacing these serine residues with alanine or aspartate has no apparent effect on GAP45 assembly into the motor protein complex or its subcellular location in the parasite. The early assembly of the motor complex suggests that it has functions in addition to its role in erythrocyte invasion.
authors.affiliation: Division of Parasitology, MRC National Institute for Medical Research, London, United Kingdom.
authors.forename: Mohd A Mohd
authors.initials: MA
authors.lastname: Ridzuan
authors.forename: Robert W
authors.initials: RW
authors.lastname: Moon
authors.forename: Ellen
authors.initials: E
authors.lastname: Knuepfer
authors.forename: Sally
authors.initials: S
authors.lastname: Black
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Holder
authors.forename: Judith L
authors.initials: JL
authors.lastname: Green
mesh_terms: D002460:Cell Line; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D010963:Plasmodium falciparum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D021381:Protein Transport; D015800:Protozoan Proteins / Q000378:metabolism; D052939:Schizonts / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D015800:Protozoan Proteins; C509918:glideosome-associated protein 45, Plasmodium falciparum; D011494:Protein Kinases; C531238:calcium-dependent protein kinase-1, Plasmodium falciparum