Affinage · Plasmodium

PF3D7_1471300

RAP protein, putative

Audit flag: identity unverified
Annotated
2026-09-08
43 papers in source corpus 10 papers cited in narrative 10 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PF3D7_1471300 (RAP-1) is a rhoptry protein of Plasmodium falciparum that serves as the scaffolding core of low-molecular-weight rhoptry protein complexes and functions after erythrocyte invasion to support intra-erythrocytic parasite development (PMID:17553576, PMID:28205319). It is synthesized as a precursor (Pr86/p80) bearing a cleavable N-terminal signal peptide and is routed to the rhoptries through the secretory pathway; transport and maturation depend on Golgi function, as brefeldin A, low temperature, and N-ethylmaleimide block conversion of Pr86 to the mature product (PMID:8719244). Once delivered to the forming rhoptries, RAP-1 is proteolytically matured by two sequential N-terminal cleavages, generating p82 and then p67, with generation of processed forms associated with schizogony and merozoite release rather than invasion (PMID:1279419, PMID:9574915). RAP-1 assembles with RAP-2 and RAP-3 into distinct RAP1/2 and RAP1/3 complexes within detergent-resistant membranes and is required to tag the surface of normal erythrocytes with rhoptry proteins, a capacity lost upon RAP-1 gene disruption but retained upon RAP-3 disruption (PMID:9574915, PMID:17553576, PMID:17624849). The complex is dispensable for rhoptry morphology and invasion itself but is needed post-invasion for parasitophorous vacuolar membrane integrity and parasite growth, and it contributes to virulence in vivo (PMID:28205319). In P. berghei, RAP-1 is additionally required to target RAP-2 to the rhoptries (PMID:29307564).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1990 Medium

    Established that RAP-1 is a single-precursor-derived, multi-component rhoptry antigen, framing all later processing work by defining the protein family of related bands as products of one gene.

    Evidence Immunoaffinity purification, SDS-PAGE, monoclonal antibody epitope analysis and sequence analysis of the rhoptry antigen in P. falciparum

    PMID:2200961

    Open questions at the time
    • Precursor-product relationships inferred immunologically, not by pulse-chase
    • No subcellular trafficking route defined
    • Function of the antigen not addressed
  2. 1992 Medium

    Showed that RAP-1 is proteolytically processed from p80 to p65 during late schizogony and that processing is linked to merozoite release rather than invasion, tying maturation to a specific stage of the parasite life cycle.

    Evidence Western blot, fusion-protein and synthetic-peptide epitope mapping, and immunoblot of purified merozoites in P. falciparum

    PMID:1279419

    Open questions at the time
    • Protease responsible for cleavage not identified
    • Functional consequence of processing not tested
    • Cleavage site mapping resolution limited
  3. 1995 High

    Defined the trafficking route by demonstrating that RAP-1 precursor maturation depends on the secretory/Golgi pathway, answering how the protein reaches the rhoptries.

    Evidence Brefeldin A, low-temperature and N-ethylmaleimide blocks, pulse-chase labeling and in vitro translation in P. falciparum

    PMID:8719244

    Open questions at the time
    • Identity of the inferred post-translational modification producing Pr86 unresolved
    • Rhoptry-specific targeting signal not mapped
  4. 1998 High

    Resolved the ordered maturation pathway (Pr86->p82->p67) and showed that RAP-1 assembles with RAP-2 and RAP-3 before processing, establishing RAP-1 as a complex-forming precursor processed after rhoptry delivery.

    Evidence Epitope-specific immunoblot, BFA-blocked size fractionation, immunofluorescence and purified merozoite analysis in P. falciparum

    PMID:9574915

    Open questions at the time
    • Stoichiometry of the complexes not quantified
    • Functional role of processed forms not tested
    • No relocalization to merozoite surface, leaving downstream role open
  5. 2007 Medium

    Confirmed RAP-1 as the core of two distinct low-molecular-weight complexes (RAP1/2, RAP1/3) within detergent-resistant membranes, defining its biochemical architecture.

    Evidence DRM purification, blue native-PAGE and mass spectrometry of P. falciparum schizonts

    PMID:17553576

    Open questions at the time
    • Nature of higher-order aggregation not characterized
    • Complex assembly determinants unknown
  6. 2007 High

    Provided the first direct functional evidence that RAP-1 is required to tag normal erythrocytes with rhoptry proteins, with RAP-3 dispensable, distinguishing RAP-1's specific role within the complex.

    Evidence RAP-1 and RAP-3 gene disruption with surface iodination and antibody binding assays on normal erythrocytes in P. falciparum

    PMID:17624849

    Open questions at the time
    • Erythrocyte receptor for the tagging not identified
    • Biological purpose of tagging not defined
  7. 2010 Medium

    Placed RAP-1 within the MSP-1-associated merozoite surface complex, linking the rhoptry protein to a surface protein network at schizont/merozoite stages.

    Evidence Anti-MSP-1 and anti-RhopH3 pull-downs with tandem mass spectrometry in P. falciparum

    PMID:21175202

    Open questions at the time
    • Direct versus indirect association not distinguished
    • Single Co-IP approach without reciprocal functional validation
    • Contradicts earlier finding that RAP-1 does not relocalize to the merozoite surface
  8. 2017 High

    Overturned the assumption that RAP-1 acts during invasion by showing the complex is dispensable for invasion but required post-invasion for PVM integrity and parasite growth, redefining its cellular role.

    Evidence Conditional knockdown with PVM electron microscopy, growth assays and in vivo mouse infection in P. falciparum and P. berghei ANKA

    PMID:28205319

    Open questions at the time
    • Molecular mechanism by which RAP-1 supports PVM structure unknown
    • Direct interaction with PVM components not shown
  9. 2018 Medium

    Demonstrated in the rodent model that RAP-1 is required for rhoptry targeting of RAP-2 and contributes to virulence, establishing a hierarchical role within the complex.

    Evidence RAP1-deficient and RAP2/3-deficient P. berghei ANKA mutants with mouse infection outcome assays

    PMID:29307564

    Open questions at the time
    • Whether RAP-1 similarly chaperones RAP-2 targeting in P. falciparum not tested here
    • Structural basis of targeting dependence unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • The molecular mechanism by which RAP-1 maintains parasitophorous vacuolar membrane integrity and its direct binding partners at the PVM remain unresolved.
  • No identified molecular target of RAP-1 at the PVM
  • Protease responsible for Pr86 processing unidentified
  • Functional role of the sequential p82/p67 maturation not tested

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
PFMSP-1RAP-2RAP-3
Complex memberships
MSP-1-associated merozoite surface complexRAP1/RAP2 low-molecular-weight rhoptry complexRAP1/RAP3 low-molecular-weight rhoptry complex

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1990 RAP-1 is a multi-component rhoptry antigen of P. falciparum consisting of four major proteins (80, 65, 42, 40 kDa) and two minor proteins (77, 70 kDa); monoclonal antibody evidence, autocatalytic processing, and immunological cross-reactivity suggest all components are derived from the same precursor protein. The antigen is lipophilic and disulphide bonding plays an important role in its structure. Immunoaffinity chromatography, SDS-PAGE, Western blot, monoclonal antibody epitope analysis, sequence analysis Molecular and biochemical parasitology Medium 2200961
1992 RAP-1 undergoes proteolytic cleavage processing from an 80-kDa precursor (p80) to a 65-kDa form (p65) during late schizogony. Inhibitory monoclonal antibodies map to a region 10–20 amino acids C-terminal to the proteolytic cleavage site at amino acid 190. The 65-kDa processed form is not present in purified merozoites, suggesting its generation is associated with merozoite release rather than erythrocyte invasion. Western blot, beta-galactosidase fusion protein epitope mapping, synthetic peptide reactivity, immunoblot of purified merozoites Molecular and biochemical parasitology Medium 1279419
1995 Transport of RAP-1 to the rhoptries is regulated by the secretory pathway. Brefeldin A (BFA) and low temperature reversibly block processing of an 86-kDa precursor (Pr86) to the mature 82-kDa RAP-1 product (p82). N-ethylmaleimide, which prevents vesicle fusion with Golgi membranes, irreversibly blocks Pr86 processing. In vitro translation reveals a cleavable N-terminal signal peptide and an initial 84-kDa primary translation product distinct from the in vivo Pr86, suggesting an undetected protein modification during maturation. Brefeldin A treatment, low-temperature block, N-ethylmaleimide treatment, pulse-chase metabolic labeling, in vitro translation Molecular and biochemical parasitology High 8719244
1998 RAP-1 products p82 and p67 are formed from the precursor Pr86 by progressive removal of epitopes from the amino-terminus. Pr86 forms complexes containing RAP-2 product p39 and RAP-3 product p37 (demonstrated after size fractionation under BFA). Pr86 is localized to rhoptries transiently and is not detected in segmenting schizonts or extracellular merozoites; p67 and p82 are major RAP-1 components in purified merozoites. Neither p67 nor p82 relocalize from rhoptries to the merozoite surface. Processing of Pr86 begins after complexes are transported to forming rhoptries, involving two sequential cleavages: rapid Pr86-to-p82, then delayed p82-to-p67. Immunoblot with epitope-specific antibodies, size fractionation under BFA, immunofluorescence localization, purified merozoite analysis Molecular and biochemical parasitology High 9574915
2007 RAP-1 is the core component of two low molecular weight rhoptry complexes (RAP1/2 and RAP1/3), identified in detergent-resistant membranes (DRMs) of P. falciparum schizonts. RAP-1 predominates in high molecular weight species by BN-PAGE, suggesting aggregation into larger complexes. DRM purification, blue native-PAGE (BN-PAGE), mass spectrometry Molecular and biochemical parasitology Medium 17553576
2007 RAP-1 and RAP-2 (members of the low molecular weight rhoptry protein complex) bind to the surface of normal (non-parasitized) erythrocytes. RAP-1 gene-disruption mutant parasites lose the capacity to tag erythrocytes with rhoptry proteins (assessed by surface iodination), demonstrating RAP-1 is required for this tagging. RAP-3 disruption did not abolish tagging. Gene disruption (RAP-1 and RAP-3 knockouts), surface iodination experiments, antibody binding assays on normal erythrocytes The Journal of infectious diseases High 17624849
2017 The RAP complex (including RAP-1) is not required for rhoptry morphology or erythrocyte invasion, but is required post-invasion for parasitophorous vacuolar membrane (PVM) structure and intra-erythrocytic parasite growth. Conditional knockdown of RAP complex members leads to altered PVM structure, delayed intra-erythrocytic growth, and reduced parasitaemias in infected mice. Conditional knockdown, electron microscopy of PVM, in vivo mouse infection assays, growth assays Cellular microbiology High 28205319
2010 RAP-1 is a component of the merozoite surface protein-1 (MSP-1) associated complex on the P. falciparum merozoite surface, co-purified alongside RAP-2, PfRhopH1, PfRhopH3, PfMSP-3, PfMSP-6, PfMSP-7, PfMSP-9, and two RAP domain-containing proteins. This complex is present at schizont/merozoite stages but not the subsequent ring stage. Pull-down with anti-PfMSP-1 and anti-PfRhopH3 antibodies, tandem mass spectrometry identification Journal of proteome research Medium 21175202
1992 Three matrix metalloproteinases (220, 95, and 70 kDa) co-isolate non-covalently with the RAP-1 complex but not with RAP-3 or gp195. These enzymes are inhibited only by EDTA (among nine proteinase inhibitors tested) and are enhanced synergistically by cobalt. However, immunoprecipitation with antisera to macrophage and fibroblast gelatinase confirmed these enzymes' identity, and they do not react with intracellular parasites by IFA, indicating the metalloproteinases originate from human serum used for in vitro culture rather than from the parasite itself. Co-isolation by immunoaffinity, proteinase inhibitor panel, metal ion dose-response, immunoprecipitation, indirect immunofluorescence Biochimica et biophysica acta Low 1477099
2018 In P. berghei, RAP-1 is required for targeting of RAP-2 to the rhoptries. RAP1-deficient P. berghei ANKA parasites showed increased early-phase parasitemia but mice survived longer; RAP2/3-deficient parasites showed low parasitemia and mice recovered from infection. These findings indicate RAP-1 and RAP-2/3 contribute to virulence. Comparative genomics, generation of RAP1-deficient and RAP2/3-deficient P. berghei ANKA mutants, mouse infection outcome assays Experimental parasitology Medium 29307564

Source papers

Stage 0 corpus · 43 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1994 Differential localization of full-length and processed forms of PF83/AMA-1 an apical membrane antigen of Plasmodium falciparum merozoites. Molecular and biochemical parasitology 229 7838184
1998 Genetic polymorphism and natural selection in the malaria parasite Plasmodium falciparum. Genetics 213 9584096
1990 A rhoptry antigen of Plasmodium falciparum is protective in Saimiri monkeys. Parasitology 92 2263413
1990 Characterisation and sequence of a protective rhoptry antigen from Plasmodium falciparum. Molecular and biochemical parasitology 90 2200961
2007 Identification of protein complexes in detergent-resistant membranes of Plasmodium falciparum schizonts. Molecular and biochemical parasitology 73 17553576
2000 Human genetic factors related to susceptibility to mild malaria in Gabon. Genes and immunity 65 11196674
2001 Limonene arrests parasite development and inhibits isoprenylation of proteins in Plasmodium falciparum. Antimicrobial agents and chemotherapy 55 11502528
1992 Inhibitory monoclonal antibodies recognise epitopes adjacent to a proteolytic cleavage site on the RAP-1 protein of Plasmodium falciparum. Molecular and biochemical parasitology 55 1279419
2010 Multiple antigen peptide vaccines against Plasmodium falciparum malaria. Infection and immunity 51 20823210
1995 The secretary pathway of plasmodium falciparum regulates transport of p82/RAP1 to the rhoptries. Molecular and biochemical parasitology 40 8719244
1998 Analysis of the processing of Plasmodium falciparum rhoptry-associated protein 1 and localization of Pr86 to schizont rhoptries and p67 to free merozoites. Molecular and biochemical parasitology 34 9574915
1998 Analysis of inhibitory epitopes in the Plasmodium falciparum rhoptry protein RAP-1 including identification of a second inhibitory epitope. Infection and immunity 33 9423886
1997 Assessment of the humoral immune response against Plasmodium falciparum rhoptry-associated proteins 1 and 2. Infection and immunity 33 9169771
2002 Plasmodium falciparum MAEBL is a unique member of the ebl family. Molecular and biochemical parasitology 32 12076768
2010 Proteome analysis reveals a large merozoite surface protein-1 associated complex on the Plasmodium falciparum merozoite surface. Journal of proteome research 31 21175202
1999 Immune responses against Plasmodium falciparum asexual blood-stage antigens and disease susceptibility in Gabonese and Cameroonian children. The American journal of tropical medicine and hygiene 31 10497996
2017 The Plasmodium rhoptry associated protein complex is important for parasitophorous vacuole membrane structure and intraerythrocytic parasite growth. Cellular microbiology 30 28205319
2007 Members of the low-molecular-mass rhoptry protein complex of Plasmodium falciparum bind to the surface of normal erythrocytes. The Journal of infectious diseases 30 17624849
1993 Specific T-cell recognition of the merozoite proteins rhoptry-associated protein 1 and erythrocyte-binding antigen 1 of Plasmodium falciparum. Infection and immunity 30 8418048
1993 Tumour necrosis factor and interleukin-6 production induced by components associated with merozoite proteins of Plasmodium falciparum. Parasite immunology 30 8506119
2009 Mechanisms of malarial anaemia: potential involvement of the Plasmodium falciparum low molecular weight rhoptry-associated proteins. Acta tropica 27 19695213
1999 IgG reactivities against recombinant Rhoptry-Associated Protein-1 (rRAP-1) are associated with mixed Plasmodium infections and protection against disease in Tanzanian children. Parasitology 25 10581610
2017 PhenoPlasm: a database of disruption phenotypes for malaria parasite genes. Wellcome open research 24 28748223
2003 Does infection with Human Immunodeficiency Virus affect the antibody responses to Plasmodium falciparum antigenic determinants in asymptomatic pregnant women? The Journal of infection 23 12643865
2010 Evidence for negative selection on the gene encoding rhoptry-associated protein 1 (RAP-1) in Plasmodium spp. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases 22 20363375
1997 Antibody responses to Rhoptry-Associated Protein-1 (RAP-1) of Plasmodium falciparum parasites in humans from areas of different malaria endemicity. Parasite immunology 20 9347514
1996 Limited RAP-1 sequence diversity in field isolates of Plasmodium falciparum. Molecular and biochemical parasitology 19 8784775
1992 Molecular factors responsible for host cell recognition and invasion in Plasmodium falciparum. The Journal of protozoology 19 1560416
1997 Evidence for distinct prototype sequences within the Plasmodium falciparum Pf60 multigene family. Molecular and biochemical parasitology 18 9233669
1995 Immunogenicity of recombinant Plasmodium falciparum rhoptry associated proteins 1 and 2. Parasite immunology 17 8834763
2001 Rhoptry-associated protein 1-binding monoclonal antibody raised against a heterologous peptide sequence inhibits Plasmodium falciparum growth in vitro. Infection and immunity 16 11254620
2009 Limited genetic polymorphism of the Plasmodium vivax low molecular weight rhoptry protein complex in the Colombian population. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases 14 20026428
2008 Effect of placental malaria and HIV infection on the antibody responses to Plasmodium falciparum in infants. The Journal of infectious diseases 14 18928377
2016 Genetic diversity and natural selection in the rhoptry-associated protein 1 (RAP-1) of recent Plasmodium knowlesi clinical isolates from Malaysia. Malaria journal 12 26847346
1998 A study of antibody and T cell recognition of rhoptry-associated protein-1 (RAP-1) and RAP-2 recombinant proteins and peptides of Plasmodium falciparum in migrants and residents of the state of Rondonia, Brazil. The American journal of tropical medicine and hygiene 12 9715934
2011 Antibodies to the Plasmodium falciparum rhoptry protein RAP-2/RSP-2 in relation to anaemia in Cameroonian children. Parasite immunology 10 21226723
2018 Comparative genomics and proteomic analyses between lethal and nonlethal strains of Plasmodium berghei. Experimental parasitology 8 29307564
2000 Putting the rap on integrin activation. Immunology today 7 11114416
1994 Characterization of a new 60 kDa apical protein of Plasmodium falciparum merozoite expressed in late schizogony. Biology of the cell 7 7606209
1992 Towards a malaria vaccine: riding the rollercoaster between unrealistic optimism and lethal pessimism. The Southeast Asian journal of tropical medicine and public health 7 1298072
2010 Conserved regions of the Plasmodium falciparum rhoptry-associated protein 3 mediate specific host-pathogen interactions during invasion of red blood cells. Peptides 4 20833215
2022 Genetic Diversity and Clustering of the Rhoptry Associated Protein-1 of Plasmodium knowlesi from Peninsular Malaysia and Malaysian Borneo. The Korean journal of parasitology 3 36588415
1992 Three matrix metalloproteinases form a non-covalent association with the rhoptry-associated protein-1 of Plasmodium falciparum. Biochimica et biophysica acta 1 1477099