Expressed in many tissues, including brain, spinal cord, kidney, liver, eye, adipose tissue, lung, epididymis, adrenal gland, pineal gland, skeletal muscle, heart, spleen, thymus, ovary, uterus, testis and epididymis. Belongs to the major facilitator (TC 2.A.1) superfamily. Organic cation transporter (TC 2.A.1.19) family.