The transport system of folic acid (Pte-Glu) by brush-border membrane vesicles (BBMV) isolated from prawn (Penaeus japonicm) 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 μM 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.
Folate Transport by Prawn Hepatopancreas Brush-Border Membrane Vesicles
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J. A. Blaya, F. J. G. Muriana, V. Ruiz-Gutierrez, C. M. Vazquez, J. Bolufer; Folate Transport by Prawn Hepatopancreas Brush-Border Membrane Vesicles. Biosci Rep 1 February 1998; 18 (1): 9–17. doi: https://doi.org/10.1023/A:1022236616277
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