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 and in kidney cortex, but not in medulla. Low levels found in brain. In the kidney, expressed specifically in the proximal and distal convoluted tubules and within Bowman capsule, but not in the glomerulus. Levels are high during gestation, but decrease greatly towards the end of gestation. Belongs to the major facilitator (TC 2.A.1) superfamily. Organic cation transporter (TC 2.A.1.19) family.