Small multidrug resistance protein
Small multidrug resistance proteins (also known as drug/metabolite transporter) are a family of integral membrane proteins that confer drug resistance to a wide range of toxic compounds including guanidinium, hydrophobic drugs, antiseptics, polyamines, and glycolipids, by removing them for the cells. Within the family there are four subtypes.
Source: Wikipedia — Small multidrug resistance protein (CC BY-SA 4.0)