{"id":"f1b8950c-26b4-5c41-8bc5-d20e61189456","stable_key":"f992b796-377d-53bf-a39b-7e5d41dbe194:b5-bio-phosphopantetheine-entry-proposal","predicate":"proposed_to_enter","statement":"The 2015 salvage paper interpreted its experiments as passive membrane entry of extracellular 4′-phosphopantetheine before conversion back to CoA.","claim_class":"hypothesis_link","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"477fc9c5-c4be-52ae-abfe-81a5a1515bfd","mechanism_event_label":"The authors proposed direct entry of the intermediate; the transport route remains a separate question from downstream enzyme activity.","subject":{"id":"aab78666-4f68-5db2-b86e-a3c6b18ed62d","slug":"phosphopantetheine","display_name":"4′-Phosphopantetheine","entity_type_key":"small_molecule"},"object":{"id":"f47adf79-faca-59ce-8453-eb907bc2c970","slug":"phosphopantetheine-cell-entry","display_name":"Cellular entry of extracellular 4′-phosphopantetheine","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"477fc9c5-c4be-52ae-abfe-81a5a1515bfd","stable_key":"f992b796-377d-53bf-a39b-7e5d41dbe194:b5-bio-phosphopantetheine-entry-proposal-event","event_type":"biochemical_relationship","label":"The authors proposed direct entry of the intermediate; the transport route remains a separate question from downstream enzyme activity.","description":"The 2015 salvage paper interpreted its experiments as passive membrane entry of extracellular 4′-phosphopantetheine before conversion back to CoA.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"485e7221-d4ad-55fc-a7f2-28caa0d05066","slug":"coasy","display_name":"Coenzyme A synthase / COASY","entity_type_key":"protein"},"role":"downstream_conversion_machinery","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"4faa6456-aff8-59eb-9e3f-3326a436e401","slug":"coenzyme-a","display_name":"Coenzyme A","entity_type_key":"small_molecule"},"role":"downstream_product","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"aab78666-4f68-5db2-b86e-a3c6b18ed62d","slug":"phosphopantetheine","display_name":"4′-Phosphopantetheine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"f47adf79-faca-59ce-8453-eb907bc2c970","slug":"phosphopantetheine-cell-entry","display_name":"Cellular entry of extracellular 4′-phosphopantetheine","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Biochemical extracellular-CoA hydrolysis and eukaryotic cell/organism salvage experiments","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Extracellular 4′-phosphopantetheine/CoA exposure; concentrations not extracted.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Author mechanistic interpretation preserved as a hypothesis. Abstract-only extraction cannot exclude extracellular dephosphorylation/rephosphorylation or establish passive uptake in every tissue, serum stability, or blood–brain-barrier delivery.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"pantothenate","display_name":"Pantothenate (vitamin B5)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Eukaryotic cell/organism models; assay-level species not specified in abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The authors proposed direct entry of the intermediate; the transport route remains a separate question from downstream enzyme activity.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[b5-bio-salvage2015] Extracellular 4'-phosphopantetheine is a source for intracellular coenzyme A synthesis. (2015). https://pubmed.ncbi.nlm.nih.gov/26322826/ DOI: 10.1038/nchembio.1906","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cell membrane and intracellular CoA synthesis","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"f174ede3-7353-5378-a010-789fa7862ca7","evidence_kind":"source_excerpt","locator":"Lines 769-780","start_line":769,"end_line":780,"excerpt":"### b5-bio-phosphopantetheine-entry-proposal\nThe 2015 salvage paper interpreted its experiments as passive membrane entry of extracellular 4′-phosphopantetheine before conversion back to CoA.\nCondition category: normal\nnutrient_topic: Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The authors proposed direct entry of the intermediate; the transport route remains a separate question from downstream enzyme activity.\norganism: Eukaryotic cell/organism models; assay-level species not specified in abstract\ntissue_or_cell_type: Cell membrane and intracellular CoA synthesis\nexperimental_model: Biochemical extracellular-CoA hydrolysis and eukaryotic cell/organism salvage experiments\nlimitations: Author mechanistic interpretation preserved as a hypothesis. Abstract-only extraction cannot exclude extracellular dephosphorylation/rephosphorylation or establish passive uptake in every tissue, serum stability, or blood–brain-barrier delivery.\nexposure: Extracellular 4′-phosphopantetheine/CoA exposure; concentrations not extracted.\ncross_nutrient: false\n[b5-bio-salvage2015] Extracellular 4'-phosphopantetheine is a source for intracellular coenzyme A synthesis. (2015). https://pubmed.ncbi.nlm.nih.gov/26322826/ DOI: 10.1038/nchembio.1906","model_system":"Biochemical extracellular-CoA hydrolysis and eukaryotic cell/organism salvage experiments","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [b5-bio-salvage2015] Extracellular 4'-phosphopantetheine is a source for intracellular coenzyme A synthesis. (2015). https://pubmed.ncbi.nlm.nih.gov/26322826/ DOI: 10.1038/nchembio.1906","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"0716b500-dd0b-5425-b9d0-d88bc9c09e86","stable_key":"import-f992b796-377d-53bf-a39b-7e5d41dbe194","title":"Pantothenic acid (vitamin B5): coenzyme A, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"b5a49f5a2373ca6064c9a4e014e052dad2f6f199a82bb09b26b82b831c36110b","revision_id":"78f3e793-f084-5ee2-8703-b661c4b650bf","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}