Ins and Outs of Major Facilitator Superfamily Antiporters

Annu Rev Microbiol. 2008;62:289-305. doi: 10.1146/annurev.micro.61.080706.093329.


The major facilitator superfamily (MFS) represents the largest group of secondary active membrane transporters, and its members transport a diverse range of substrates. Recent work shows that MFS antiporters, and perhaps all members of the MFS, share the same three-dimensional structure, consisting of two domains that surround a substrate translocation pore. The advent of crystal structures of three MFS antiporters sheds light on their fundamental mechanism; they operate via a single binding site, alternating-access mechanism that involves a rocker-switch type movement of the two halves of the protein. In the sn-glycerol-3-phosphate transporter (GlpT) from Escherichia coli, the substrate-binding site is formed by several charged residues and a histidine that can be protonated. Salt-bridge formation and breakage are involved in the conformational changes of the protein during transport. In this review, we attempt to give an account of a set of mechanistic principles that characterize all MFS antiporters.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Antiporters / chemistry*
  • Antiporters / metabolism*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Binding Sites
  • Escherichia coli Proteins
  • Kinetics
  • Membrane Transport Proteins / chemistry
  • Membrane Transport Proteins / metabolism
  • Models, Molecular
  • Protein Conformation


  • Antiporters
  • Bacterial Proteins
  • EmrD protein, E coli
  • Escherichia coli Proteins
  • GlpT protein, E coli
  • Membrane Transport Proteins
  • OxlT protein, bacteria