Cell membrane polyamine/proton antiporter, involved in the detoxification of excess polyamines in the cytoplasm. Catalyzes polyamine uptake at alkaline pH and excretion at acidic pH. Recognizes spermidine, spermine and putrescine, the polyamine analogs methylglyoxal bis(guanylhydrazone) (MGBG) and paraquat, the antimalarial drug quinidine, and cycloheximide. Confers resistance to the non-steroidal anti-inflammatory drug indomethacin. Enriched on the cell membrane of growing buds. By transcription factor PDR1, by transcription factor HAA1 in response to acetaldehyde accumulation and by the non-steroidal anti-inflammatory drug indomethacin. Present with 1470 molecules/cell in log phase SD medium. Belongs to the major facilitator superfamily. DHA1 family. Polyamines/proton antiporter (TC 2.A.1.2.16) subfamily.