{"id":"9a967359-8077-5c35-863b-090e453a8204","stable_key":"649e861b-265a-5912-bc36-3a73e53ef892:l-serine-psat-genetic","predicate":"loses_capacity_with","statement":"Recombinant PSAT1 Asp100Ala retained only about 15% of wild-type maximal activity in the study of two affected siblings.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"7be66b5f-d4ba-5968-8516-4eb68f11e33c","mechanism_event_label":"The amino-group transfer step can become a synthesis bottleneck.","subject":{"id":"a549bab7-965e-57f9-99b3-e8dfcb535af5","slug":"psat1","display_name":"Human phosphoserine aminotransferase / PSAT1","entity_type_key":"protein"},"object":{"id":"531e1a30-6f2c-5782-ae67-cd64b99e2809","slug":"human-psat1-d100a-activity","display_name":"Human PSAT1 Asp100Ala catalytic activity","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"7be66b5f-d4ba-5968-8516-4eb68f11e33c","stable_key":"649e861b-265a-5912-bc36-3a73e53ef892:l-serine-psat-genetic-event","event_type":"observed_relationship","label":"The amino-group transfer step can become a synthesis bottleneck.","description":"Recombinant PSAT1 Asp100Ala retained only about 15% of wild-type maximal activity in the study of two affected siblings.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"a549bab7-965e-57f9-99b3-e8dfcb535af5","slug":"psat1","display_name":"Human phosphoserine aminotransferase / PSAT1","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"531e1a30-6f2c-5782-ae67-cd64b99e2809","slug":"human-psat1-d100a-activity","display_name":"Human PSAT1 Asp100Ala catalytic activity","entity_type_key":"cellular_process"},"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":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human family genetics and recombinant mutant expression.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Fibroblast enzyme testing was inconclusive; the recombinant result is the direct functional measurement.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Serine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-serine","display_name":"L-Serine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"The amino-group transfer step can become a synthesis bottleneck.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Phosphoserine aminotransferase deficiency: a novel disorder of the serine biosynthesis pathway. · 2007 · https://pubmed.ncbi.nlm.nih.gov/17436247/ · DOI 10.1086/517888","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"d02513d9-51b3-54e5-8df2-88b1466eb263","evidence_kind":"source_excerpt","locator":"Lines 102-108","start_line":102,"end_line":108,"excerpt":"## l-serine-psat-genetic\nThe amino-group transfer step can become a synthesis bottleneck.\nRecombinant PSAT1 Asp100Ala retained only about 15% of wild-type maximal activity in the study of two affected siblings.\nModel: Human family genetics and recombinant mutant expression.\nLimitations: Fibroblast enzyme testing was inconclusive; the recombinant result is the direct functional measurement.\nEvidence access: Primary abstract\nPhosphoserine aminotransferase deficiency: a novel disorder of the serine biosynthesis pathway. · 2007 · https://pubmed.ncbi.nlm.nih.gov/17436247/ · DOI 10.1086/517888","model_system":"Human family genetics and recombinant mutant expression.","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":"70bcf57a-36bb-563f-9073-2d616e5f155a","stable_key":"import-649e861b-265a-5912-bc36-3a73e53ef892","title":"L-Serine: synthesis, one-carbon metabolism, lipids 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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