SLC29A4 encodes the plasma membrane monoamine transporter (PMAT), an electrogenic voltage-dependent transporter that mediates cellular uptake of bioactive amines and organic cations 123. PMAT utilizes the inside-negative membrane potential to facilitate organic cation transport in a Na+- and Cl−-independent, bidirectional manner 123. Transport is pH-dependent and enhanced under acidic conditions 453. PMAT transports monoamine neurotransmitters including serotonin, dopamine, norepinephrine, and histamine, supporting aminergic neurotransmission regulation 167. The transporter localizes to the apical membrane of choroid plexus epithelium, clearing cationic neurotoxins and xenobiotics from cerebrospinal fluid 8. PMAT dysfunction associates with autism spectrum disorder through impaired serotonin transport 9, type 2 diabetes and metformin intolerance via reduced metformin clearance 1011, and inflammatory bowel disease and postpartum depression risk 1213. PMAT also transports adenosine bidirectionally in cardiac tissue during ischemia 45. Sex-dependent behavioral responses to antidepressants suggest PMAT functions as a secondary monoamine transporter when primary transporters are saturated or blocked 14.