Facilitative organic cation transporter that mediates the transport of carnitine as well as the polyamine spermidine (, ). Mediates the partially Na(+)-dependent bidirectional transport of carnitine . May mediate L-carnitine secretion from testis epididymal epithelium into the lumen which is involved in the maturation of spermatozoa .
Subcellular locations: Cell membrane
Detected in the plasma membrane of Sertoli cells and in the luminal membrane of epithelial cells in the epididymis.
Expressed in testis and epididymis (at protein level) ( ). Expressed in endometrium (at protein level); highly expressed during the normal secretory phase, but expression is significantly reduced in the proliferative phase . Expressed at lower levels in adult tissues including bone marrow (at protein level) ( ). Expressed in hematopoietic cells, including CD34(+) leukocytes . Expressed in fetal liver (at protein level), brain, lung, kidney, heart, skeletal muscle, spleen and thymus ( ). Expressed in leukemia cells . Abundantly expressed in ovarian cancer clear-cell adenocarcinoma .