A Comparison of Sepiapterin and Tetrahydrobiopterin Uptake by BRL2H3 Cells

Abstract

Cellular uptake of sepiapterin and tetrahydrobiopterin was compared quantitatively with RBL2H3 cells in culture. RBL2H3 is a mast cell line and has the ability to synthesize serotonin. Sepiapterin was incorporated and converted into tetrahydrobiopterin in the cell. The incorporation of sepiapterin was about 10 times faster than tetrahydrobiopterin. A low concentration of tetrahydrobiopterin was incorporated in a saturable manner up to about 10 μM, and it was superimposed upon a linearly concentration- dependent process. Overnight treatment with DAHP depleted endogenous tetrahydrobiopterin. The DAHP treated cells took up tetrahydrobiopterin faster than untreated cells.