Lactose permease as a paradigm for membrane transport proteins (Review).
Our structural knowledge of the major facilitator superfamily (MFS) has dramatically increased in the past year with three structures of proteins from the MFS (oxalate/formate antiporter; lactose/proton symporter and the P(i)/glycerol-3-phosphate antiporter). All three structures revealed 12 transmembrane helices forming two distinct domains and could imply that members of the MFS have preserved both secondary as well as tertiary structural elements during evolution. Lactose permease, a particularly well-studied member of the MFS, has been extensively explored by a number of molecular biological, biochemical and biophysical approaches. In this review, we take a closer look at the structure of LacY and incorporate a wealth of biochemical and biophysical data in order to propose a possible mechanism for lactose/proton symport. In addition, we make some brief comparisons between the structures of LacY and GlpT.
Abramson
Jeff
J
Department of Biological Sciences, Imperial College London, London SW7 2AZ, UK.
Iwata
So
S
Kaback
H Ronald
HR
D000818:Animals; D001665:Binding Sites; D001692:Biological Transport; D006801:Humans; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011522:Protons
D026901:Membrane Transport Proteins; D011522:Protons; C021499:lactose permease