{"id":"fb52ab8b-3ee8-54dd-aa85-bee57659b560","stable_key":"97957230-601f-5dec-8524-0812be8fadbf:l-threonine-bicarbonate-limitation","predicate":"limits","statement":"The measured bicarbonate/CO2 Km for t6A37 formation was 31 millimolar; human cells cultured without bicarbonate had less t6A37 in mitochondrial tRNAs.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"1519cedd-b518-5600-ae2f-6711fdeeccce","mechanism_event_label":"An additional substrate can limit the threonine-dependent reaction.","subject":{"id":"edf44f6b-7b23-5b97-a86b-c940e5812b06","slug":"bicarbonate-ion","display_name":"Bicarbonate ion","entity_type_key":"ion"},"object":{"id":"5c27b149-da7e-5a90-8bd3-d4b2a42bb2ef","slug":"trna-threonylcarbamoyladenosine","display_name":"tRNA-bound N6-threonylcarbamoyladenosine / t6A37","entity_type_key":"rna"},"evidence_count":1,"mechanism_event":{"id":"1519cedd-b518-5600-ae2f-6711fdeeccce","stable_key":"97957230-601f-5dec-8524-0812be8fadbf:l-threonine-bicarbonate-limitation-event","event_type":"observed_relationship","label":"An additional substrate can limit the threonine-dependent reaction.","description":"The measured bicarbonate/CO2 Km for t6A37 formation was 31 millimolar; human cells cultured without bicarbonate had less t6A37 in mitochondrial tRNAs.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"edf44f6b-7b23-5b97-a86b-c940e5812b06","slug":"bicarbonate-ion","display_name":"Bicarbonate ion","entity_type_key":"ion"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"5c27b149-da7e-5a90-8bd3-d4b2a42bb2ef","slug":"trna-threonylcarbamoyladenosine","display_name":"tRNA-bound N6-threonylcarbamoyladenosine / t6A37","entity_type_key":"rna"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"fcef4dc2-a7b6-5812-bc33-c8af3d83f4d0","slug":"l-threonine","display_name":"L-Threonine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"58b974f1-d389-5bf6-81cd-889c44442c42","slug":"atp","display_name":"ATP","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"3114b5d2-04d2-59d6-88c3-c04eb28aeeff","slug":"yrdc","display_name":"Human threonylcarbamoyladenylate synthase / YRDC","entity_type_key":"protein"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"f28550d6-0143-5fe3-ae30-1e634dbd024d","slug":"osgepl1","display_name":"Human mitochondrial tRNA threonylcarbamoyltransferase / OSGEPL1","entity_type_key":"protein"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Reconstituted enzyme kinetics and bicarbonate-deprived human cell culture.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"The culture manipulation is not a bicarbonate supplementation trial or a clinical intracellular threshold.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Threonine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-threonine","display_name":"L-Threonine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"An additional substrate can limit the threonine-dependent reaction.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"CO2-sensitive tRNA modification associated with human mitochondrial disease. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29760464/ · DOI 10.1038/s41467-018-04250-4","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"97879f3f-b329-5559-b241-0e7e88c26de9","evidence_kind":"source_excerpt","locator":"Lines 138-144","start_line":138,"end_line":144,"excerpt":"## l-threonine-bicarbonate-limitation\nAn additional substrate can limit the threonine-dependent reaction.\nThe measured bicarbonate/CO2 Km for t6A37 formation was 31 millimolar; human cells cultured without bicarbonate had less t6A37 in mitochondrial tRNAs.\nModel: Reconstituted enzyme kinetics and bicarbonate-deprived human cell culture.\nLimitations: The culture manipulation is not a bicarbonate supplementation trial or a clinical intracellular threshold.\nEvidence access: Primary abstract\nCO2-sensitive tRNA modification associated with human mitochondrial disease. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29760464/ · DOI 10.1038/s41467-018-04250-4","model_system":"Reconstituted enzyme kinetics and bicarbonate-deprived human cell culture.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"35396730-235a-537e-8a05-c6ef2960c509","stable_key":"import-97957230-601f-5dec-8524-0812be8fadbf","title":"L-Threonine: translation, intestinal barrier, metabolism and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. 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