title: A complex of three related membrane proteins is conserved on malarial merozoites.
abstract: Invasion of human red blood cells by the malaria parasite Plasmodium falciparum is a coordinated, multi-step process. Here, we describe three novel integral membrane proteins that colocalize on the inner membrane complex immediately beneath the merozoite plasma membrane. Each has six predicted transmembrane domains and is conserved in diverse apicomplexan parasites. Immunoprecipitation studies using specific antibodies reveal that these proteins assemble into a heteromeric complex. Each protein was also expressed on insect cells using the baculovirus vector system with a truncated SUMO tag that facilitates maximal expression and protein purification while permitting cleavage with SUMO protease to release unmodified parasite protein. The expressed proteins were successfully reconstituted into artificial liposomes, but were not recognized by human immune sera. Because all three genes are highly conserved in apicomplexan parasites, the complex formed by their encoded proteins likely serves an essential role for invasive merozoites.
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Kempaiah
authors.initials: K
authors.lastname: Rayavara
authors.forename: Thavamani
authors.initials: T
authors.lastname: Rajapandi
authors.forename: Kurt
authors.initials: K
authors.lastname: Wollenberg
authors.forename: Juraj
authors.initials: J
authors.lastname: Kabat
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Fischer
authors.forename: Sanjay A
authors.initials: SA
authors.lastname: Desai
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry*; D017124:Conserved Sequence; D005822:Genetic Vectors; D006801:Humans; D047468:Immunoprecipitation; D007313:Insecta; D008565:Membrane Proteins / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D052940:Merozoites / Q000737:chemistry*; D008954:Models, Biological; D008958:Models, Molecular; D010802:Phylogeny; D010963:Plasmodium falciparum / Q000737:chemistry* / Q000235:genetics; D055503:Protein Multimerization; D015800:Protozoan Proteins / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid
chemical_list: D000913:Antibodies, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins