Structure and mechanism of the glycerol-3-phosphate transporter from Escherichia coli

Science. 2003 Aug 1;301(5633):616-20. doi: 10.1126/science.1087619.


The major facilitator superfamily represents the largest group of secondary membrane transporters in the cell. Here we report the 3.3 angstrom resolution structure of a member of this superfamily, GlpT, which transports glycerol-3-phosphate into the cytoplasm and inorganic phosphate into the periplasm. The amino- and carboxyl-terminal halves of the protein exhibit a pseudo two-fold symmetry. Closed off to the periplasm, a centrally located substrate-translocation pore contains two arginines at its closed end, which comprise the substrate-binding site. Upon substrate binding, the protein adopts a more compact conformation. We propose that GlpT operates by a single-binding site, alternating-access mechanism through a rocker-switch type of movement.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Biological Transport
  • Cell Membrane / chemistry
  • Crystallization
  • Crystallography, X-Ray
  • Escherichia coli / chemistry*
  • Escherichia coli / enzymology
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / metabolism
  • Glycerophosphates / metabolism*
  • Helix-Turn-Helix Motifs
  • Mass Spectrometry
  • Membrane Transport Proteins / chemistry*
  • Membrane Transport Proteins / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Periplasm / metabolism
  • Phosphates / metabolism
  • Protein Conformation
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary


  • Escherichia coli Proteins
  • GlpT protein, E coli
  • Glycerophosphates
  • Membrane Transport Proteins
  • Phosphates
  • alpha-glycerophosphoric acid

Associated data

  • PDB/1PW4