{"id":"379684d5-2dad-5c8a-b874-728e26044ad7","stable_key":"aaa7baba-8689-56ab-ba1e-b71542bcb8e9:iodine-trans-sodium-affinity","predicate":"increases_affinity","statement":"Thermodynamic fits to rat IEC-6 NIS transport data estimated an iodide Kd of 224 micromolar without sodium binding and 22.4 micromolar in the sodium-bound state.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"5c70cd38-22b6-5e17-bee3-2a21deb72cb2","mechanism_event_label":"Sodium binding makes NIS bind iodide more readily.","subject":{"id":"38de8704-84db-5770-ac1d-242cd787e798","slug":"sodium-ion","display_name":"Sodium ion","entity_type_key":"ion"},"object":{"id":"76042f0e-b2b5-559d-ba75-74aeb2d4bc22","slug":"nis-iodide-affinity","display_name":"NIS affinity for iodide","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"5c70cd38-22b6-5e17-bee3-2a21deb72cb2","stable_key":"aaa7baba-8689-56ab-ba1e-b71542bcb8e9:iodine-trans-sodium-affinity-event","event_type":"biochemical_relationship","label":"Sodium binding makes NIS bind iodide more readily.","description":"Thermodynamic fits to rat IEC-6 NIS transport data estimated an iodide Kd of 224 micromolar without sodium binding and 22.4 micromolar in the sodium-bound state.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"acfbc5ec-b299-5365-8c5d-9e492c18d1d9","slug":"rat-slc5a5","display_name":"Rat sodium/iodide symporter / Slc5a5","entity_type_key":"protein"},"role":"transporter","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"38de8704-84db-5770-ac1d-242cd787e798","slug":"sodium-ion","display_name":"Sodium ion","entity_type_key":"ion"},"role":"allosteric_cotransported_ion","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"83b11ca6-52c7-5a1b-8c39-d9cdf89244e3","slug":"iodide","display_name":"Iodide ion","entity_type_key":"ion"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"76042f0e-b2b5-559d-ba75-74aeb2d4bc22","slug":"nis-iodide-affinity","display_name":"NIS affinity for iodide","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Endogenous rat NIS in IEC-6 intestinal epithelial cells; initial-rate transport and statistical thermodynamic fitting","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Initial-rate iodide uptake at 5, 10, 20 or 60 micromolar iodide with 0–260 mM sodium; two-minute incubations; constant osmolarity.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Kd values depend on the authors’ transport model; the finding does not show that eating extra salt improves iodine status.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Iodine research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"iodine","display_name":"Iodine","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Rattus norvegicus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Sodium binding makes NIS bind iodide more readily.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[iodine-trans-sodium-affinity2014] Physiological sodium concentrations enhance the iodide affinity of the Na+/I- symporter. (2014). https://pubmed.ncbi.nlm.nih.gov/24888603/ DOI: 10.1038/ncomms4948","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"IEC-6 intestinal epithelial cells","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"a2f8716a-5a8e-5909-a1e2-d2146b554441","evidence_kind":"source_excerpt","locator":"Lines 180-191","start_line":180,"end_line":191,"excerpt":"### iodine-trans-sodium-affinity\nThermodynamic fits to rat IEC-6 NIS transport data estimated an iodide Kd of 224 micromolar without sodium binding and 22.4 micromolar in the sodium-bound state.\nCondition category: normal\nnutrient_topic: Iodine research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Sodium binding makes NIS bind iodide more readily.\norganism: Rattus norvegicus\ntissue_or_cell_type: IEC-6 intestinal epithelial cells\nexperimental_model: Endogenous rat NIS in IEC-6 intestinal epithelial cells; initial-rate transport and statistical thermodynamic fitting\nlimitations: Kd values depend on the authors’ transport model; the finding does not show that eating extra salt improves iodine status.\nexposure: Initial-rate iodide uptake at 5, 10, 20 or 60 micromolar iodide with 0–260 mM sodium; two-minute incubations; constant osmolarity.\ncross_nutrient: true\n[iodine-trans-sodium-affinity2014] Physiological sodium concentrations enhance the iodide affinity of the Na+/I- symporter. 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