Mediates potential-dependent transport of a variety of organic cations. May play a significant role in the disposition of cationic neurotoxins and neurotransmitters in the brain. Highly expressed in placenta. Moderate expression in intestine, heart and brain. In the brain, widely expressed, especially in hippocampus, cerebellum and cerebral cortex. Expression is low in kidney and lung and undetectable in liver. Belongs to the major facilitator (TC 2.A.1) superfamily. Organic cation transporter (TC 2.A.1.19) family.