Protein Domain : Small multidrug resistance protein IPR045324

Type	Family
Description	Members of this family are integral membrane proteins that belong to the small multidrug resistance (SMR) protein family. They confer resistance to a wide range of toxic compounds by removing them for the cells. The efflux is coupled to an influx of protons. An example is Escherichia coli EmrE ( ) which plays a role in pH and osmotic stress response and biofilm formation. It confers resistance to a wide range of toxic compounds, including ethidium, methyl viologen [ , ], benzalkonium, propidium, dequalinium, different aromatic cation antibiotics, being also involved in ethidium bromide efflux [, ]. It simultaneously binds and co-transports proton and drug [, ]. Structural studies of EmrE revealed that the transmembrane (TM) helices undergo a complex reorientation to bind and transport diverse substrates. It may function not only as a proton-coupled antiporter but also as a proton-coupled symporter or uncoupled uniporter that potentially confers susceptibility rather than resistance, because the inward proton motive force and negative-inside membrane potential in bacteria would lead to concentrative uptake of toxic cations [].
Short Name	Small_multidrug_res