Electrogenic voltage-dependent transporter that mediates the transport of a variety of organic cations such as endogenous bioactive amines, cationic drugs and xenobiotics. Cation cellular uptake or release is driven by the electrochemical potential, i.e. membrane potential and concentration gradient. Functions as a Na(+)- and Cl(-)-independent, bidirectional uniporter. Implicated in monoamine neurotransmitters uptake such as dopamine, adrenaline/epinephrine, noradrenaline/norepinephrine, histamine, serotonin and tyramine, thereby supporting a role in homeostatic regulation of aminergic neurotransmission in the brain. Transports dopaminergic neuromodulators cyclo(his-pro) and salsolinol with low efficiency. May be involved in the uptake and disposition of cationic compounds by renal clearance from the blood flow. May contribute to regulate the transport of cationic compounds in testis across the blood-testis-barrier (Probable). Mediates the transport of polyamine spermidine and putrescine. Mediates the bidirectional transport of polyamine agmatine. Also transports guanidine. May also mediate intracellular transport of organic cations, thereby playing a role in amine metabolism and intracellular signaling.