major facilitator superfamily (MFS) antibiotic efflux pump antibiotic_resistance ARO:0010002 MFS type drug efflux Directed pumping of antibiotic out of a cell to confer resistance. Major facilitator superfamily (MFS) transporters and ABC transporters comprise the two largest and most functionally diverse of the transporter superfamilies. However, MFS transporters are distinct from ABC transporters in both their primary sequence and structure and in the mechanism of energy coupling. As secondary transporters they are, like RND and SMR transporters, energized by the electrochemical proton gradient. efflux pump complex or subunit conferring antibiotic resistance