title: An approach to membrane protein structure without crystals.
abstract: The lactose permease of Escherichia coli catalyzes coupled translocation of galactosides and H(+) across the cell membrane. It is the best-characterized member of the Major Facilitator Superfamily, a related group of membrane proteins with 12 transmembrane domains that mediate transport of various substrates across cell membranes. Despite decades of effort and their functional importance in all kingdoms of life, no high-resolution structures have been solved for any member of this family. However, extensive biochemical, genetic, and biophysical studies on lactose permease have established its transmembrane topology, secondary structure, and numerous interhelical contacts. Here we demonstrate that this information is sufficient to calculate a structural model at the level of helix packing or better.
authors.affiliation: Biochemistry Department, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Sorgen
authors.forename: Yonglin
authors.initials: Y
authors.lastname: Hu
authors.forename: Lan
authors.initials: L
authors.lastname: Guan
authors.forename: H Ronald
authors.initials: HR
authors.lastname: Kaback
authors.forename: Mark E
authors.initials: ME
authors.lastname: Girvin
mesh_terms: D001665:Binding Sites; D003460:Crystallization; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins / Q000737:chemistry*; D008958:Models, Molecular; D009004:Monosaccharide Transport Proteins; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D017434:Protein Structure, Tertiary; D027981:Symporters
chemical_list: D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; C021499:lactose permease