Sodium-ion dependent, high affinity carnitine transporter. Involved in the active cellular uptake of carnitine. 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 11.3 ( ). In intestinal epithelia, transports the quorum-sensing pentapeptide CSF (competence and sporulation factor) from Bacillus Subtilis wich induces cytoprotective heat shock proteins contributing to intestinal homeostasis . May also contribute to regulate the transport of organic compounds in testis across the blood-testis-barrier (Probable).
Retained in the ER, unable to perform carnitine uptake.
Subcellular locations: Cell membrane, Apical cell membrane, Basal cell membrane
In intestinal cells, apical expression is induced by TNF. Localized to the basal membrane of Sertoli cells .
Subcellular locations: Endoplasmic reticulum
Strongly expressed in kidney, skeletal muscle, heart and placenta . Primarily expressed by surface epithelial cells of the colon (at protein level) . Expressed in CD68 macrophage and CD43 T-cells but not in CD20 B-cells . In testis, localized to Sertoli cell basal membranes, peritubular myoid cells and Leydig cells .