{"id":"b52c16b1-d67d-5b22-ac65-3f94c877fd70","stable_key":"0f17db03-207f-5910-ac8e-13dfc2f378ce:mg-romk2-low-external-k-enhances-block","predicate":"modulates-magnesium-block-of","statement":"Lower external K+ increased the apparent affinity of cytoplasmic Mg2+ block of rat ROMK2 and permitted block over physiologically relevant negative voltages.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"51a78635-50d3-5d68-aa60-bd0ceebe0367","mechanism_event_label":"The potassium concentration outside the cell changes how strongly inside Mg restrains potassium exit.","subject":{"id":"5dd31e52-f51e-51f3-880e-240abcc0ab1d","slug":"potassium-ion","display_name":"Potassium ion","entity_type_key":"ion"},"object":{"id":"36040e51-774a-5206-8f4d-2a22794e1c22","slug":"romk2","display_name":"ROMK2 splice isoform","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"51a78635-50d3-5d68-aa60-bd0ceebe0367","stable_key":"0f17db03-207f-5910-ac8e-13dfc2f378ce:mg-romk2-low-external-k-enhances-block-event","event_type":"biochemical_relationship","label":"The potassium concentration outside the cell changes how strongly inside Mg restrains potassium exit.","description":"Lower external K+ increased the apparent affinity of cytoplasmic Mg2+ block of rat ROMK2 and permitted block over physiologically relevant negative voltages.","status":"provisional","compartment":{"slug":"plasma-membrane","display_name":"Plasma membrane"},"participants":[{"entity":{"id":"bff427ab-35f9-59c2-bb24-fd5953bbaec2","slug":"magnesium-ion","display_name":"Mg2+","entity_type_key":"ion"},"role":"intracellular blocker","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"5dd31e52-f51e-51f3-880e-240abcc0ab1d","slug":"potassium-ion","display_name":"Potassium ion","entity_type_key":"ion"},"role":"external concentration variable","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"36040e51-774a-5206-8f4d-2a22794e1c22","slug":"romk2","display_name":"ROMK2 splice isoform","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"magnesium -> potassium","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Heterologous channel expression and patch-clamp","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"External K tested at 110, 11 and 1.1 mM; experimental concentrations, not dietary targets.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Excised-patch channel behavior does not quantify whole-body potassium loss in humans.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Magnesium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"magnesium","display_name":"Magnesium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Xenopus laevis host; mammalian ROMK channel","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The potassium concentration outside the cell changes how strongly inside Mg restrains potassium exit.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[yang-2010-romk-magnesium] Magnesium modulates ROMK channel-mediated potassium secretion (2010). https://pubmed.ncbi.nlm.nih.gov/21030597/ DOI: 10.1681/ASN.2010060617","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Oocyte membrane","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"ac4039a5-1439-5307-a892-8c463f380f6f","evidence_kind":"source_excerpt","locator":"Lines 116-127","start_line":116,"end_line":127,"excerpt":"### mg-romk2-low-external-k-enhances-block\nLower external K+ increased the apparent affinity of cytoplasmic Mg2+ block of rat ROMK2 and permitted block over physiologically relevant negative voltages.\nCondition category: normal\nnutrient_topic: Magnesium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The potassium concentration outside the cell changes how strongly inside Mg restrains potassium exit.\norganism: Xenopus laevis host; mammalian ROMK channel\ntissue_or_cell_type: Oocyte membrane\nexperimental_model: Heterologous channel expression and patch-clamp\nlimitations: Excised-patch channel behavior does not quantify whole-body potassium loss in humans.\ncross_nutrient: magnesium -> potassium\nexposure: External K tested at 110, 11 and 1.1 mM; experimental concentrations, not dietary targets.\n[yang-2010-romk-magnesium] Magnesium modulates ROMK channel-mediated potassium secretion (2010). https://pubmed.ncbi.nlm.nih.gov/21030597/ DOI: 10.1681/ASN.2010060617","model_system":"Heterologous channel expression and patch-clamp","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [yang-2010-romk-magnesium] Magnesium modulates ROMK channel-mediated potassium secretion (2010). https://pubmed.ncbi.nlm.nih.gov/21030597/ DOI: 10.1681/ASN.2010060617","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"dd101e28-1a2e-5a48-9d1e-809c77514866","stable_key":"import-0f17db03-207f-5910-ac8e-13dfc2f378ce","title":"Magnesium: cross-nutrient mechanisms and deficiency (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":"e111c412f57143a17e8e65e74e8f7888b5bb9a61099873f4767f527fac19bb07","revision_id":"6b7f04f2-66ed-5859-955f-c2b50d4bf041","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}