{"id":"2ce077cb-dd70-59dd-b453-f6a974395141","stable_key":"97957230-601f-5dec-8524-0812be8fadbf:l-threonine-serine-competition-slc1a5","predicate":"inhibits_serine_uptake_via","statement":"L-threonine inhibited radiolabeled L-serine uptake in HEK cells expressing human ASCT2, with an IC50 of 228 ± 83 micromolar.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"a7a92d19-fc39-5fc7-8edd-58dc81da0ddd","mechanism_event_label":"Threonine can compete with serine in a defined transporter assay.","subject":{"id":"fcef4dc2-a7b6-5812-bc33-c8af3d83f4d0","slug":"l-threonine","display_name":"L-Threonine","entity_type_key":"small_molecule"},"object":{"id":"e77d1b7d-6156-59ce-96d9-11876f57f033","slug":"slc1a5","display_name":"Human neutral amino acid exchanger ASCT2 / SLC1A5","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"a7a92d19-fc39-5fc7-8edd-58dc81da0ddd","stable_key":"97957230-601f-5dec-8524-0812be8fadbf:l-threonine-serine-competition-slc1a5-event","event_type":"observed_relationship","label":"Threonine can compete with serine in a defined transporter assay.","description":"L-threonine inhibited radiolabeled L-serine uptake in HEK cells expressing human ASCT2, with an IC50 of 228 ± 83 micromolar.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"fcef4dc2-a7b6-5812-bc33-c8af3d83f4d0","slug":"l-threonine","display_name":"L-Threonine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"e77d1b7d-6156-59ce-96d9-11876f57f033","slug":"slc1a5","display_name":"Human neutral amino acid exchanger ASCT2 / SLC1A5","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"c882cd0b-9d83-5b07-bd1c-fe4d45657dcb","slug":"l-serine","display_name":"L-Serine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full-text Table 5, publisher PDF","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Table 5: three observations per transporter; heterologous human-transporter HEK cell assays.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"An inhibition concentration in culture is not a dietary threshold or proof of reduced brain serine.","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":"Threonine can compete with serine in a defined transporter assay.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"D-Serine Is a Substrate for Neutral Amino Acid Transporters ASCT1/SLC1A4 and ASCT2/SLC1A5, and Is Transported by Both Subtypes in Rat Hippocampal Astrocyte Cultures. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27272177/ · DOI 10.1371/journal.pone.0156551","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"4ce7a072-53d5-51ea-9138-09dc8ecf4b3e","evidence_kind":"source_excerpt","locator":"Lines 34-40","start_line":34,"end_line":40,"excerpt":"## l-threonine-serine-competition-slc1a5\nThreonine can compete with serine in a defined transporter assay.\nL-threonine inhibited radiolabeled L-serine uptake in HEK cells expressing human ASCT2, with an IC50 of 228 ± 83 micromolar.\nModel: Table 5: three observations per transporter; heterologous human-transporter HEK cell assays.\nLimitations: An inhibition concentration in culture is not a dietary threshold or proof of reduced brain serine.\nEvidence access: Primary full-text Table 5, publisher PDF\nD-Serine Is a Substrate for Neutral Amino Acid Transporters ASCT1/SLC1A4 and ASCT2/SLC1A5, and Is Transported by Both Subtypes in Rat Hippocampal Astrocyte Cultures. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27272177/ · DOI 10.1371/journal.pone.0156551","model_system":"Table 5: three observations per transporter; heterologous human-transporter HEK cell assays.","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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