5 outermost layer of cells in contact w food folate

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Unformatted text preview: 7/2014 Folate absorption Foodfolatepredominately polyglutamateform  Two ­stepprocess: 1)Hydrolysis  ­GCPII 2)Absorption Saturable Non ­saturable   Step1:Hydrolysis Glutamatecarboxypeptidase II(GCPII) Cleavesfood polyglutamatesinjejunalbrush bordertomonoglutamate Actsasanexopeptidase cleavingterminal glutamates pHoptimumis6.5 outermost layer of cells in contact w food/ folate   Monoglutamate Foodfolate reducedpolyglutamate Glutamate Glutamate Glutamate Glutamate Glutamate GCPII Glutamate Glutamate 5 1/7/2014 Step2:Absorption  ­saturable Carrier ­mediatedprocess saturablein dietaryrangeofconcentration  Intestinaluptakeoffolateismediatedby: Proton ­CoupledFolateTransporter(PCFT)   ­transmembraneproteinlocatedonapical  membraneofenterocyte FolateAbsorptioninDuodenum Folate (polyglutamate) Folate (monoglutamate) Lumen PCFT GCPII Apical membrane Basolateral membrane MRP3 multidrug resistance-associated protein 3 Portal blood Step2:Absorption non ­saturable  Withoutatransporter  Folateintakeinpharmacologicalrange  Supplements,fortifiedfoods some people are absorbing it through passive diffusion 6 1/7/2014 Effectofalcoholonabsorption Chronicalcoholconsumption: DecreasesactivityofGCPII Decreasesl...
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