SLC46A1 protein in the plasma membrane mediates the reversible transport of folate between the extracellular space and the cytosol. Retention of folate within the cell is dependent on polyglutamate addition. Although the SLC46A1 gene is expressed in several tissues in the body, this transporter appears to be primarily needed for absorption of dietary folate from the intestinal lumen (Qiu et al. 2006; Chen et al. 1996).