2.A.68.1.2
The drug resistance permease, MtrF (Folster and Shafer, 2005).  The 3-d structure is known (Su et al. 2015). MtrF is a bowl-shaped dimer with a solvent-filled basin extending from the cytoplasm to halfway across the membrane bilayer (Su et al. 2015). Each subunit of the transporter contains nine transmembrane helices and two hairpins, posing a plausible pathway for substrate transport. A combination of the crystal structure and biochemical functional assays suggests that MtrF is an antibiotic efflux pump mediating bacterial resistance to sulfonamide antimetabolite drugs (Su et al. 2015). MtrF and YdaH, (TC#2.A.68.1.4) and the dicarboxylate transporter, INDY (TC#2.a.47.5.2) have been shown to have the same 3-d fold (Vergara-Jaque et al. 2015), confirming the assignment of these two families to the same superfamily (Prakash et al. 2003).