{"id":"e8d32fa0-cc7f-5f10-9a2f-bb26b07e3614","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:ca-ncx1-calcium-sodium-exchange","predicate":"transports","statement":"Human cardiac NCX1 exchanges calcium and sodium in opposing directions across the membrane.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"ca3c8b67-93a5-50b7-9f80-110da754358e","mechanism_event_label":"NCX1 couples calcium movement to sodium moving the other way.","subject":{"id":"e3a8401d-1368-5851-879d-c5fa748650da","slug":"slc8a1","display_name":"Na+/Ca2+ exchanger 1 / SLC8A1","entity_type_key":"protein"},"object":{"id":"e359bc15-e675-5d83-b0fe-1d70814e130b","slug":"calcium-ion","display_name":"Calcium ion","entity_type_key":"ion"},"evidence_count":1,"mechanism_event":{"id":"ca3c8b67-93a5-50b7-9f80-110da754358e","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:ca-ncx1-calcium-sodium-exchange-event","event_type":"transport","label":"NCX1 couples calcium movement to sodium moving the other way.","description":"Human cardiac NCX1 exchanges calcium and sodium in opposing directions across the membrane.","status":"provisional","compartment":{"slug":"plasma-membrane","display_name":"Plasma membrane"},"participants":[{"entity":{"id":"e3a8401d-1368-5851-879d-c5fa748650da","slug":"slc8a1","display_name":"Na+/Ca2+ exchanger 1 / SLC8A1","entity_type_key":"protein"},"role":"exchanger","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"e359bc15-e675-5d83-b0fe-1d70814e130b","slug":"calcium-ion","display_name":"Calcium ion","entity_type_key":"ion"},"role":"transported_substrate","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"38de8704-84db-5770-ac1d-242cd787e798","slug":"sodium-ion","display_name":"Sodium ion","entity_type_key":"ion"},"role":"countertransported_ion","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"f0b6bcb6-5d41-5d9d-af9f-6af1a94d5c5a","slug":"plasma-membrane","display_name":"Plasma membrane","entity_type_key":"organelle"},"role":"experimental_location","stoichiometry":null,"state_label":"","sequence_order":3,"notes":"Study location; presence here is not a separate transport or causal claim."}]},"contexts":[{"dimension":"compartment_description","value_text":"Plasma membrane","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human cardiac NCX1; cryo-EM and functional exchange assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Net direction depends on electrochemical gradients and voltage; NCX1 is not an ATP-hydrolyzing pump.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Calcium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"NCX1 couples calcium movement to sodium moving the other way.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[ca-xue2023] Structural mechanisms of the human cardiac sodium-calcium exchanger NCX1 (2023). https://pubmed.ncbi.nlm.nih.gov/37794011/ DOI: 10.1038/s41467-023-41885-4","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"research_relationship_category","value_text":"transport","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cardiac NCX1 expression system","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"transport_effect","value_text":"depends","comparator":null,"unit":null,"notes":"Reversible exchange: forward mode extrudes calcium and reverse mode admits it, which the record states.","entity":null},{"dimension":"transport_or_reaction_direction","value_text":"Reversible Na+/Ca2+ exchange; forward calcium extrusion or reverse calcium entry","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"transport_pool","value_text":"cytosolic calcium","comparator":null,"unit":null,"notes":"Reversible exchange: forward mode extrudes calcium and reverse mode admits it, which the record states.","entity":null}],"evidence":[{"id":"b289b965-8308-5917-ac89-537f7a9a624d","evidence_kind":"source_excerpt","locator":"Lines 625-637","start_line":625,"end_line":637,"excerpt":"### ca-ncx1-calcium-sodium-exchange\nHuman cardiac NCX1 exchanges calcium and sodium in opposing directions across the membrane.\nCondition category: normal\nnutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: NCX1 couples calcium movement to sodium moving the other way.\norganism: Homo sapiens\ntissue_or_cell_type: Cardiac NCX1 expression system\nexperimental_model: Human cardiac NCX1; cryo-EM and functional exchange assays\nlimitations: Net direction depends on electrochemical gradients and voltage; NCX1 is not an ATP-hydrolyzing pump.\nresearch_relationship_category: transport\ntransport_or_reaction_direction: Reversible Na+/Ca2+ exchange; forward calcium extrusion or reverse calcium entry\ncompartment_description: Plasma membrane\n[ca-xue2023] Structural mechanisms of the human cardiac sodium-calcium exchanger NCX1 (2023). https://pubmed.ncbi.nlm.nih.gov/37794011/ DOI: 10.1038/s41467-023-41885-4","model_system":"Human cardiac NCX1; cryo-EM and functional exchange assays","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [ca-xue2023] Structural mechanisms of the human cardiac sodium-calcium exchanger NCX1 (2023). https://pubmed.ncbi.nlm.nih.gov/37794011/ DOI: 10.1038/s41467-023-41885-4","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"3c083fa0-59c6-50e9-af42-678d0e3c1006","stable_key":"import-434e1e27-eb90-583a-956b-62472726ffba","title":"Calcium: mechanism-first literature curation (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":"965c934d6b147f2b62f8d45ce6d7a87681a600bfe5c46a585b4704889afd3fc1","revision_id":"543ec48b-4f70-5197-9d76-f5a3c443664c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}