{"id":"a96b69b9-52d9-54ba-a692-93973ac9e65b","stable_key":"46d15d9e-d3b5-544d-ba01-b785aa3e4f42:b1-slc44a4-apical-targeting","predicate":"localizes-to","statement":"SLC44A4 isoform-1 fusion protein predominantly localized to the apical domain of polarized MDCK cells.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"1390c720-68bc-5059-b19f-24b50857a955","mechanism_event_label":"Its membrane targeting fits entry from the gut lumen.","subject":{"id":"38c31209-2363-5275-a271-8abb0ce92cdc","slug":"slc44a4-isoform-1","display_name":"Human SLC44A4 isoform 1","entity_type_key":"protein"},"object":{"id":"32984346-b954-5281-8f94-9eff6e500af3","slug":"intestinal-epithelium","display_name":"Intestinal epithelium","entity_type_key":"tissue"},"evidence_count":1,"mechanism_event":{"id":"1390c720-68bc-5059-b19f-24b50857a955","stable_key":"46d15d9e-d3b5-544d-ba01-b785aa3e4f42:b1-slc44a4-apical-targeting-event","event_type":"biochemical_relationship","label":"Its membrane targeting fits entry from the gut lumen.","description":"SLC44A4 isoform-1 fusion protein predominantly localized to the apical domain of polarized MDCK cells.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"187db168-8028-5ce6-9f8b-4bc61ebad1a0","slug":"thiamine-diphosphate","display_name":"Thiamine diphosphate","entity_type_key":"small_molecule"},"role":"transport substrate","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"38c31209-2363-5275-a271-8abb0ce92cdc","slug":"slc44a4-isoform-1","display_name":"Human SLC44A4 isoform 1","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"32984346-b954-5281-8f94-9eff6e500af3","slug":"intestinal-epithelium","display_name":"Intestinal epithelium","entity_type_key":"tissue"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence-scope","value_text":"ARPE19; MDCK; human colon","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_locator","value_text":"Figure 8","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_spans","value_text":"[{\"source_document\": \"artifacts/thiamine_transport_sources/PMC3924303.txt\", \"start_char\": 47362, \"end_char\": 48692}]","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human SLC44A4 isoforms expressed in ARPE19 cells; polarized MDCK imaging.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Canine model expressing human protein; not direct transepithelial flux.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Thiamine research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"thiamine","display_name":"Thiamine (vitamin B1)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Human constructs; human and canine host cells","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Its membrane targeting fits entry from the gut lumen.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[nabokina-2014-slc44a4] Molecular identification and functional characterization of the human colonic thiamine pyrophosphate transporter (2014). https://pmc.ncbi.nlm.nih.gov/articles/PMC3924303/ DOI: 10.1074/jbc.M113.528257","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"spatial_context","value_text":"Apical membrane of polarized epithelial model.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"ARPE19; MDCK; human colon","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"2d12e9e0-a255-55f3-a853-7a0a6c98a1dd","evidence_kind":"source_excerpt","locator":"Lines 545-558","start_line":545,"end_line":558,"excerpt":"### b1-slc44a4-apical-targeting\nSLC44A4 isoform-1 fusion protein predominantly localized to the apical domain of polarized MDCK cells.\nCondition category: normal\nnutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Its membrane targeting fits entry from the gut lumen.\norganism: Human constructs; human and canine host cells\ntissue_or_cell_type: ARPE19; MDCK; human colon\nexperimental_model: Human SLC44A4 isoforms expressed in ARPE19 cells; polarized MDCK imaging.\nlimitations: Canine model expressing human protein; not direct transepithelial flux.\nevidence_locator: Figure 8\nspatial_context: Apical membrane of polarized epithelial model.\nevidence_spans: [{\"source_document\": \"artifacts/thiamine_transport_sources/PMC3924303.txt\", \"start_char\": 47362, \"end_char\": 48692}]\nevidence-scope: ARPE19; MDCK; human colon\n[nabokina-2014-slc44a4] Molecular identification and functional characterization of the human colonic thiamine pyrophosphate transporter (2014). https://pmc.ncbi.nlm.nih.gov/articles/PMC3924303/ DOI: 10.1074/jbc.M113.528257","model_system":"Human SLC44A4 isoforms expressed in ARPE19 cells; polarized MDCK imaging.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [nabokina-2014-slc44a4] Molecular identification and functional characterization of the human colonic thiamine pyrophosphate transporter (2014). https://pmc.ncbi.nlm.nih.gov/articles/PMC3924303/ DOI: 10.1074/jbc.M113.528257","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"158d2c03-ac8c-589f-8270-c468165ae346","stable_key":"import-46d15d9e-d3b5-544d-ba01-b785aa3e4f42","title":"Thiamine: mechanisms, deficiency and nutrient interactions (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":"f376512fb3310141315548015b387833e3af45146e73fb73cd02cee20e4ddb9c","revision_id":"53bc5eda-dec8-58cc-a56f-a9eb4ab036ef","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}