Uptake and metabolism of biotin by human peripheral blood mononuclear cells |
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Authors: | Zempleni, Janos Mock, Donald M. |
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Abstract: | We studied the uptake of biotin into human peripheral bloodmononuclear cells (PBMC) using[3H]biotin and studiedthe catabolism of biotin in PBMC using[14C]biotin. Over 30 min, [3H]biotin uptakewas greater at 37°C than at 25°C(KT = 2.6 ± 0.4 nM, maximal velocity = 2.9 ± 0.2 fmol · 106cells1 · 30 min1). Ouabain reduced[3H]biotin uptake to65% of control values, suggesting that biotin uptake is Na-K-ATPasedependent. Unlabeled biotin and biotin analogs reduced the uptake of[3H]biotin to22-70% of control values, suggesting the presence of acompetition for a structurally specific biotin transporter. Whenendocytosis by PBMC was stimulated by various acyl glycerols, [3H]biotin uptake was40-73% of control values; these data are consistent with thehypothesis that stimulated endocytosis reduces biotin transporterdensity on the cell surface. During a 168-h incubation, PBMC did notcatabolize[14C]biotin. |
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