{"gene":"PF3D7_1108700","run_date":"2026-09-08T12:51:28","timeline":{"discoveries":[{"year":2021,"finding":"Pfj2 (PF3D7_1108700) is an ER-localized chaperone belonging to the Thioredoxin superfamily that is essential for asexual P. falciparum survival, as demonstrated by conditional knockdown mutants that failed to complete asexual growth.","method":"Conditional knockdown mutant generation with asexual growth phenotype readout","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean conditional knockdown with defined lethal phenotype in asexual stages, ER localization established, single lab with multiple orthogonal methods","pmids":["33534803"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"Using a redox-active crosslinker specific for redox-active cysteines, Pfj2 was shown to interact with PfPDI8 and PfPDI11 (both Trx superfamily members) as substrates, identifying a redox-regulatory role for Pfj2 in the parasite ER.","method":"Redox-active crosslinker pulldown followed by mass spectrometry (crosslink-MS)","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — substrate identification by redox-specific crosslinker + MS, single lab, mechanistically specific method","pmids":["33534803"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"PfPDI8, one of the Pfj2 substrates identified by redox crosslinking, is required for asexual parasite growth and genetic epistasis data suggest it may work in a complex with Pfj2 and other ER chaperones; by contrast, PfPDI11 knockdown in Pfj2 conditional mutants indicated PfPDI11 is not essential.","method":"Conditional knockdown of PfPDI8 and PfPDI11 in Pfj2 conditional mutant background (double mutant epistasis) with asexual growth readout","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — epistasis via double conditional knockdown, single lab, phenotype clearly defined but complex membership inferred rather than biochemically reconstituted","pmids":["33534803"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"The redox interactions between Pfj2 and its Trx-domain protein substrates in the P. falciparum ER are sensitive to small molecule inhibition, establishing the Pfj2-centered oxidative folding network as a druggable target.","method":"Small molecule inhibitor treatment of Pfj2 conditional mutants with parasite growth and redox interaction readouts","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional inhibition demonstrated in the context of mechanistically characterized redox network, single lab, multiple orthogonal approaches","pmids":["33534803"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"Pfj2 (PF3D7_1108700) is an essential ER-localized chaperone and Thioredoxin superfamily member in P. falciparum that forms a redox-active complex with PfPDI8 (and possibly other ER chaperones) to mediate oxidative protein folding in the parasite ER, with its redox interactions being sensitive to small molecule inhibition."},"narrative":{"mechanistic_narrative":"Pfj2 (PF3D7_1108700) is an endoplasmic reticulum-localized chaperone of the Thioredoxin superfamily that is essential for asexual blood-stage survival of Plasmodium falciparum, where it functions at the center of an oxidative protein-folding network [PMID:33534803]. Using a redox-active crosslinker that traps interactions between redox-active cysteines, Pfj2 was shown to engage the Trx-superfamily proteins PfPDI8 and PfPDI11 as redox substrates in the parasite ER [PMID:33534803]. Genetic epistasis places PfPDI8 in a functional complex with Pfj2 and additional ER chaperones and shows PfPDI8 is itself required for asexual growth, whereas PfPDI11 is dispensable [PMID:33534803]. The redox interactions between Pfj2 and its Trx-domain substrates are sensitive to small-molecule inhibition, establishing this Pfj2-centered oxidative folding network as a druggable target [PMID:33534803]. All available evidence derives from a single study; beyond this ER redox-chaperone role, no further mechanistic detail has been characterized in the available corpus.","teleology":[{"year":2021,"claim":"Establishing that Pfj2 is an essential ER chaperone answered whether this Thioredoxin-superfamily protein has a non-redundant role in parasite biology.","evidence":"conditional knockdown mutants with asexual growth phenotype readout, plus ER localization","pmids":["33534803"],"confidence":"High","gaps":["molecular chaperone activity not reconstituted biochemically","role in sexual/other life-cycle stages not tested","no structural model of Pfj2"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Identifying PfPDI8 and PfPDI11 as redox substrates defined the molecular partners through which Pfj2 acts in ER oxidative folding.","evidence":"redox-active crosslinker pulldown followed by mass spectrometry in P. falciparum","pmids":["33534803"],"confidence":"Medium","gaps":["direct enzymatic redox transfer between Pfj2 and substrates not reconstituted in vitro","full substrate/interactome scope beyond the two PDIs unknown","stoichiometry and directionality of the redox reaction undefined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Double conditional knockdown epistasis distinguished which Pfj2 substrates are functionally essential, placing PfPDI8 in a shared complex while showing PfPDI11 is dispensable.","evidence":"conditional knockdown of PfPDI8 and PfPDI11 in a Pfj2 conditional mutant background with asexual growth readout","pmids":["33534803"],"confidence":"Medium","gaps":["complex membership inferred genetically, not biochemically reconstituted","identity of the 'other ER chaperones' in the proposed complex not resolved","architecture and stoichiometry of the Pfj2-PfPDI8 complex unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"Demonstrating that the Pfj2 redox interactions are inhibitable by small molecules established the network as a candidate antimalarial target.","evidence":"small-molecule inhibitor treatment of Pfj2 conditional mutants with parasite growth and redox-interaction readouts","pmids":["33534803"],"confidence":"Medium","gaps":["molecular target/binding site of the inhibitor not defined","selectivity over host chaperones not established","no lead-optimization or in vivo efficacy data"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"How Pfj2 mechanistically couples its chaperone (J-domain) activity to redox chemistry, and the full architecture of its ER folding complex, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["no biochemical reconstitution of Pfj2 redox/chaperone activity","no structural data on Pfj2 or its complexes","all evidence from a single study/lab"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Pfj2-PfPDI8 ER oxidative-folding complex (with additional ER chaperones, inferred genetically) [#2]"],"partners":["PFPDI8 (REDOX SUBSTRATE; ESSENTIAL, SHARED COMPLEX) [#1, #2]","PFPDI11 (REDOX SUBSTRATE; NON-ESSENTIAL) [#1, #2]"],"other_free_text":["Essential for asexual P. falciparum blood-stage growth [#0]","Redox interactions with Trx-domain substrates are sensitive to small-molecule inhibition, marking the network as druggable [#3]","All findings derive from a single 2021 study; no independent replication in the corpus"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"9274886","id":"PMC_9274886","title":"Cloning and characterization of heat shock protein DnaJ homologues from Plasmodium falciparum and comparison with ring infected erythrocyte surface antigen.","date":"1997","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/9274886","citation_count":28,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28322872","id":"PMC_28322872","title":"Plasmodium Hsp40 and human Hsp70: A potential cochaperone-chaperone complex.","date":"2017","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/28322872","citation_count":23,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33534803","id":"PMC_33534803","title":"A redox-active crosslinker reveals an essential and inhibitable oxidative folding network in the endoplasmic reticulum of malaria parasites.","date":"2021","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/33534803","citation_count":14,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["Pfj2","PfJ2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34880324","id":"PMC_34880324","title":"Essential role of a Plasmodium berghei heat shock protein (PBANKA_0938300) in gametocyte development.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/34880324","citation_count":9,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["HSPJ62"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":4383,"output_tokens":1502,"usd":0.01784,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5873,"output_tokens":2173,"usd":0.041845,"stage2_stop_reason":"end_turn"},"total_usd":0.059685,"stage1_batch_id":"msgbatch_01DisAaTypwmC8QwdMBuePHo","stage2_batch_id":"msgbatch_0184zxZTqxiEfdYYfPMfkqjb","note":"batch pricing = 50% of standard"},"stage1_raw":"I need to carefully evaluate each paper for mechanistic findings about PF3D7_1108700 (Pfj2/PfJ2).\n\n**Paper [1] PMID:9274886** — Cloning/characterization of DnaJ homologues. No abstract provided; likely describes cloning and sequence comparison. Cannot extract specific mechanistic findings without abstract text.\n\n**Paper [2] PMID:28322872** — About PEXEL-motif-containing Type II PfDNAJ proteins interacting with hHsp70. PF3D7_1108700 is an ER-localized chaperone (not exported/PEXEL-containing), so this paper is about other PfHsp40 family members, not Pfj2 specifically. SKIP.\n\n**Paper [3] PMID:33534803** — Explicitly studies \"PfJ2\" as an ER chaperone/Trx superfamily member. This is clearly about PF3D7_1108700. Contains multiple mechanistic findings: essentiality, ER localization, substrates (PfPDI8, PfPDI11), complex formation, redox-active crosslinker experiments.\n\n**Paper [4] PMID:34880324** — Studies P. berghei \"HspJ62\" in gametocyte development. Need to assess if this is the ortholog of PF3D7_1108700 (Pfj2). The naming \"HspJ62\" and \"PBANKA_0938300\" could be the ortholog, but the gene symbol and description differ significantly from Pfj2 (which is an ER Trx-domain protein). HspJ62 appears to be a different HSP40 family member. SKIP as likely a different paralog.\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2021,\n      \"finding\": \"Pfj2 (PF3D7_1108700) is an ER-localized chaperone belonging to the Thioredoxin superfamily that is essential for asexual P. falciparum survival, as demonstrated by conditional knockdown mutants that failed to complete asexual growth.\",\n      \"method\": \"Conditional knockdown mutant generation with asexual growth phenotype readout\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean conditional knockdown with defined lethal phenotype in asexual stages, ER localization established, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"33534803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Using a redox-active crosslinker specific for redox-active cysteines, Pfj2 was shown to interact with PfPDI8 and PfPDI11 (both Trx superfamily members) as substrates, identifying a redox-regulatory role for Pfj2 in the parasite ER.\",\n      \"method\": \"Redox-active crosslinker pulldown followed by mass spectrometry (crosslink-MS)\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — substrate identification by redox-specific crosslinker + MS, single lab, mechanistically specific method\",\n      \"pmids\": [\"33534803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PfPDI8, one of the Pfj2 substrates identified by redox crosslinking, is required for asexual parasite growth and genetic epistasis data suggest it may work in a complex with Pfj2 and other ER chaperones; by contrast, PfPDI11 knockdown in Pfj2 conditional mutants indicated PfPDI11 is not essential.\",\n      \"method\": \"Conditional knockdown of PfPDI8 and PfPDI11 in Pfj2 conditional mutant background (double mutant epistasis) with asexual growth readout\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — epistasis via double conditional knockdown, single lab, phenotype clearly defined but complex membership inferred rather than biochemically reconstituted\",\n      \"pmids\": [\"33534803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The redox interactions between Pfj2 and its Trx-domain protein substrates in the P. falciparum ER are sensitive to small molecule inhibition, establishing the Pfj2-centered oxidative folding network as a druggable target.\",\n      \"method\": \"Small molecule inhibitor treatment of Pfj2 conditional mutants with parasite growth and redox interaction readouts\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional inhibition demonstrated in the context of mechanistically characterized redox network, single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"33534803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"Pfj2 (PF3D7_1108700) is an essential ER-localized chaperone and Thioredoxin superfamily member in P. falciparum that forms a redox-active complex with PfPDI8 (and possibly other ER chaperones) to mediate oxidative protein folding in the parasite ER, with its redox interactions being sensitive to small molecule inhibition.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"Pfj2 (PF3D7_1108700) is an endoplasmic reticulum-localized chaperone of the Thioredoxin superfamily that is essential for asexual blood-stage survival of Plasmodium falciparum, where it functions at the center of an oxidative protein-folding network [#0]. Using a redox-active crosslinker that traps interactions between redox-active cysteines, Pfj2 was shown to engage the Trx-superfamily proteins PfPDI8 and PfPDI11 as redox substrates in the parasite ER [#1]. Genetic epistasis places PfPDI8 in a functional complex with Pfj2 and additional ER chaperones and shows PfPDI8 is itself required for asexual growth, whereas PfPDI11 is dispensable [#2]. The redox interactions between Pfj2 and its Trx-domain substrates are sensitive to small-molecule inhibition, establishing this Pfj2-centered oxidative folding network as a druggable target [#3]. All available evidence derives from a single study; beyond this ER redox-chaperone role, no further mechanistic detail has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2021,\n      \"claim\": \"Establishing that Pfj2 is an essential ER chaperone answered whether this Thioredoxin-superfamily protein has a non-redundant role in parasite biology.\",\n      \"evidence\": \"conditional knockdown mutants with asexual growth phenotype readout, plus ER localization\",\n      \"pmids\": [\"33534803\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"molecular chaperone activity not reconstituted biochemically\",\n        \"role in sexual/other life-cycle stages not tested\",\n        \"no structural model of Pfj2\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identifying PfPDI8 and PfPDI11 as redox substrates defined the molecular partners through which Pfj2 acts in ER oxidative folding.\",\n      \"evidence\": \"redox-active crosslinker pulldown followed by mass spectrometry in P. falciparum\",\n      \"pmids\": [\"33534803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"direct enzymatic redox transfer between Pfj2 and substrates not reconstituted in vitro\",\n        \"full substrate/interactome scope beyond the two PDIs unknown\",\n        \"stoichiometry and directionality of the redox reaction undefined\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Double conditional knockdown epistasis distinguished which Pfj2 substrates are functionally essential, placing PfPDI8 in a shared complex while showing PfPDI11 is dispensable.\",\n      \"evidence\": \"conditional knockdown of PfPDI8 and PfPDI11 in a Pfj2 conditional mutant background with asexual growth readout\",\n      \"pmids\": [\"33534803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"complex membership inferred genetically, not biochemically reconstituted\",\n        \"identity of the 'other ER chaperones' in the proposed complex not resolved\",\n        \"architecture and stoichiometry of the Pfj2-PfPDI8 complex unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating that the Pfj2 redox interactions are inhibitable by small molecules established the network as a candidate antimalarial target.\",\n      \"evidence\": \"small-molecule inhibitor treatment of Pfj2 conditional mutants with parasite growth and redox-interaction readouts\",\n      \"pmids\": [\"33534803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"molecular target/binding site of the inhibitor not defined\",\n        \"selectivity over host chaperones not established\",\n        \"no lead-optimization or in vivo efficacy data\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How Pfj2 mechanistically couples its chaperone (J-domain) activity to redox chemistry, and the full architecture of its ER folding complex, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"no biochemical reconstitution of Pfj2 redox/chaperone activity\",\n        \"no structural data on Pfj2 or its complexes\",\n        \"all evidence from a single study/lab\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003756\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0051082\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006457\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0034976\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [\n      \"Pfj2-PfPDI8 ER oxidative-folding complex (with additional ER chaperones, inferred genetically) [#2]\"\n    ],\n    \"partners\": [\n      \"PfPDI8 (redox substrate; essential, shared complex) [#1, #2]\",\n      \"PfPDI11 (redox substrate; non-essential) [#1, #2]\"\n    ],\n    \"other_free_text\": [\n      \"Essential for asexual P. falciparum blood-stage growth [#0]\",\n      \"Redox interactions with Trx-domain substrates are sensitive to small-molecule inhibition, marking the network as druggable [#3]\",\n      \"All findings derive from a single 2021 study; no independent replication in the corpus\"\n    ]\n  }\n}","audit_flag":{"gene":"PF3D7_1108700","tier":"IDENTITY_CHECK","verdict":"identity unverified","subtype":"names_other_cards","uniprot_band":"","rules_fired":"R12","issue":"No cited paper names this card; 1 of 1 cited papers name other catalogue genes (PF3D7_0827900, PF3D7_1134100). The summary may describe one of those genes."},"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1108700","name":null,"product":"heat shock protein J2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0938300","name":null,"product":"heat shock protein J2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0906300","name":null,"product":"heat shock protein J2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"Pfj2","evaluation":null}