SLC46A1

• OMIM: 611 672
• UniProt: Q96NT5

The proton- coupled Folattransporter ( PCFT ) (also heme carrier) is a protein that is found in the cell wall of cells of chordates. It facilitates the influx of folic acid and heme into the cell interior ( cytosol ). Therefore, it is a transport protein. Human PCFT is located mainly in the kidneys, liver, placenta, small intestine, spleen and retina. Mutations in the SLC46A1 gene can lead to transporter deficiency, and this for the ( rare ) hereditary folate malabsorption.

Heme in food is an important source of iron. In excess iron in the body PCFT is transported in intestinal cells from the apical side of the membrane to the cytosol; the reverse process takes place in iron deficiency. In the cell, the iron is released from the porphyrin and transported in the blood plasma.

Folatüberschuss resulted in cell cultures resulted in a significant decrease in the expression of all folattransportierenden proteins ( PCFT, RFC, folate receptor ) in intestinal cells.

The antifolate pemetrexed is transported by PCFT. Similar to ferroportin the production of PCFT is down-regulated in macrophages in inflammation. Dexamethasone activates the expression.

The catalyzed membrane transport of PCFT:

It is a symport. The affinity for folate as a substrate is greater than heme. The working area for the transport of folic acid at pH 4.0 to 5.5.