Cys294 is essential for the function of the human sodium-dependent multivitamin transporter

► A significant inhibition in biotin uptake occurs upon mutating Cys294. ► The effect is not related to polar status of substituted cysteine residue. ► The inhibition is mediated via significant decrease in Vmax of the biotin uptake. ► Mutating Cys294 leads to a marked reduction in surface expression of hSMVT.