{"id":"82961fcf-2084-5474-a6b0-8e8bcfa57aa7","stable_key":"97957230-601f-5dec-8524-0812be8fadbf:l-threonine-galnt2-sugar","predicate":"glycosylates","statement":"GalNAc-T2 initiates mucin-type O-glycosylation by transferring GalNAc from UDP-GalNAc to serine or threonine residues within proteins.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"fb268046-c1d1-5c39-8f42-03326d835ba5","mechanism_event_label":"A threonine residue already built into a protein can carry a sugar.","subject":{"id":"2c25648b-ab89-5f6e-9fd5-c623abc65d15","slug":"galnt2","display_name":"Human polypeptide GalNAc transferase 2 / GALNT2","entity_type_key":"protein"},"object":{"id":"0b8a4e76-bf31-527d-83a3-f37f6e945e10","slug":"protein-bound-threonine","display_name":"Protein-bound L-threonine residue","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"fb268046-c1d1-5c39-8f42-03326d835ba5","stable_key":"97957230-601f-5dec-8524-0812be8fadbf:l-threonine-galnt2-sugar-event","event_type":"observed_relationship","label":"A threonine residue already built into a protein can carry a sugar.","description":"GalNAc-T2 initiates mucin-type O-glycosylation by transferring GalNAc from UDP-GalNAc to serine or threonine residues within proteins.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"2c25648b-ab89-5f6e-9fd5-c623abc65d15","slug":"galnt2","display_name":"Human polypeptide GalNAc transferase 2 / GALNT2","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"0b8a4e76-bf31-527d-83a3-f37f6e945e10","slug":"protein-bound-threonine","display_name":"Protein-bound L-threonine residue","entity_type_key":"small_molecule"},"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":"42c9cea9-1d97-5a7c-b4f0-cbefc9fc23ab","slug":"udp-n-acetylgalactosamine","display_name":"UDP-N-acetylgalactosamine / UDP-GalNAc","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"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":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human GalNAc-T2 structural and NMR enzymology.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Free dietary threonine is not the glycosyltransferase acceptor used in this protein-modification reaction.","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":"A threonine residue already built into a protein can carry a sugar.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Structural Analysis of a GalNAc-T2 Mutant Reveals an Induced-Fit Catalytic Mechanism for GalNAc-Ts. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29601100/ · DOI 10.1002/chem.201800701","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"b66fa9bf-0f30-566e-a880-e655ecf54d7f","evidence_kind":"source_excerpt","locator":"Lines 186-192","start_line":186,"end_line":192,"excerpt":"## l-threonine-galnt2-sugar\nA threonine residue already built into a protein can carry a sugar.\nGalNAc-T2 initiates mucin-type O-glycosylation by transferring GalNAc from UDP-GalNAc to serine or threonine residues within proteins.\nModel: Human GalNAc-T2 structural and NMR enzymology.\nLimitations: Free dietary threonine is not the glycosyltransferase acceptor used in this protein-modification reaction.\nEvidence access: Primary abstract\nStructural Analysis of a GalNAc-T2 Mutant Reveals an Induced-Fit Catalytic Mechanism for GalNAc-Ts. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29601100/ · DOI 10.1002/chem.201800701","model_system":"Human GalNAc-T2 structural and NMR enzymology.","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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