Sodium-ion dependent, low affinity carnitine transporter. Probably transports one sodium ion with one molecule of carnitine. Also transports organic cations such as tetraethylammonium (TEA) without the involvement of sodium. Relative uptake activity ratio of carnitine to TEA is 1.78. A key substrate of this transporter seems to be ergothioneine (ET). More active at neutral and alkaline pHs than at acidic pHs. Interacts with PDZK1. 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. Expressed in CD68 macrophage and CD43 T-cells but not in CD20 B-cells. Predominantly expressed in CD14 cells in peripheral blood mononuclear cells. Overexpressed upon TNF treatment. Disease susceptibility is associated with variants affecting the gene represented in this entry. Belongs to the major facilitator (TC 2.A.1) superfamily. Organic cation transporter (TC 2.A.1.19) family. PubMed:9426230 reported that this protein does not transport carnitine, however, experiments were done with the Phe-503 variant, which affects the ability to transport carnitine. PubMed:15459889 showed that, although weakly, it can also transport carnitine at some level. Its function in carnitine transport is therefore unclear.