Biotin transport in a human intestinal epithelial cell line (Caco-2).
The apical (AP)-to-basolateral (BL) transport of [3H]biotin across Caco-2 cell monolayers grown on a Transwell polycarbonate membrane was shown to be dependent on days in culture, reaching a maximum at 10 days. The AP-to-BL transport of [3H]biotin was always much greater than the BL-to-AP transport. AP-to-BL transport of [3H]biotin was concentration-(Km = 1.49 microM and Vmax = 1.86 pmol.mg protein-1.minute-1), temperature-, Na(+)- and energy-dependent, and proceeded against a concentration gradient in the BL side. [3H]Biotin transport was inhibited by unlabeled biotin and several structural analogues (e.g., desthiobiotin and biotin methyl ester) but not by taurocholic acid. No metabolism of [3H]biotin was detected in the AP-to-BL transport across Caco-2 cell monolayers. This study demonstrates that [3H]biotin transport in Caco-2 cells occurs by a carrier-mediated process.
Department of Pharmaceutical Chemistry, University of Kansas, Lawrence 66045.
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D001693:Biological Transport, Active; D001710:Biotin / Q000493:pharmacokinetics*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004847:Epithelial Cells; D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*
D001710:Biotin