title: Folate transport by prawn hepatopancreas brush-border membrane vesicles.
abstract: The transport system of folic acid (Pte-Glu) by brush-border membrane vesicles (BBMV) isolated from prawn (Penaeus japonicus) hepatopancreas, was studied by measuring the uptake of Pte-Glu. This uptake was found to have two components, intravesicular transport and membrane binding. Membrane binding was not affected by the presence of a transmembrane pH-gradient at a short incubation period. However, a transmembrane pH-gradient increased membrane binding at 60 min. The transport of Pte-Glu appeared to be carrier-mediated, was stimulated by an inwardly proton gradient (pH 5.5 outside, 7.4 inside) and was unaffected by a sodium-gradient. The relationship between pH gradient-driven Pte-Glu uptake and medium Pte-Glu concentration followed saturating Michaelis-Menten kinetics. Eadie-Hofstee representation of the pH gradient-driven Pte-Glu uptake indicated a single transport system with a Km of 0.37 microM and Vmax of 1.06 pmol/mg protein/15 s. These findings indicate that BBMV isolated from prawn hepatopancreas possesses a Pte-Glu transport system similar to that described in mammalian intestine.
authors.affiliation: Departamento de Fisiología y Biología Animal, Facultad de Farmacía, Sevilla, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Blaya
authors.forename: F J
authors.initials: FJ
authors.lastname: Muriana
authors.forename: V
authors.initials: V
authors.lastname: Ruiz-Gutierrez
authors.forename: C M
authors.initials: CM
authors.lastname: Vazquez
authors.forename: J
authors.initials: J
authors.lastname: Bolufer
mesh_terms: D000818:Animals; D001692:Biological Transport; D033364:Decapoda / Q000378:metabolism*; D004064:Digestive System / Q000378:metabolism*; D005492:Folic Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008871:Microvilli / Q000378:metabolism
chemical_list: D005492:Folic Acid