The encoded protein is an integral protein of the plasma membrane containing 12 transmembrane segments. The first functional designation of this protein was OCTN1 but efficiency of transport for organic cations is very low.The transport efficiency for carnitine is also negligible. Instead, the protein is responsible for the cotransport of sodium ions and ergothioneine, which is an antioxidant, into cells. Thus, a more appropriate functional designation is ETT ("ergothioneine transporter").Widely expressed. Highly expressed in whole blood, bone marrow, trachea and fetal liver. Weakly expressed in kidney, skeletal muscle, prostate, lung, pancreas, placenta, heart, uterus, spleen and spinal cord. Highly expressed in intestinal cell types affected by Crohn disease, including epithelial cells.