title: Shared Molecular Mechanisms of Membrane Transporters.
abstract: The determination of the crystal structures of small-molecule transporters has shed light on the conformational changes that take place during structural isomerization from outward- to inward-facing states. Rather than using a simple rocking movement of two bundles around a central substrate-binding site, it has become clear that even the most simplistic transporters utilize rearrangements of nonrigid bodies. In the most dramatic cases, one bundle is fixed while the other, structurally divergent, bundle carries the substrate some 18 Å across the membrane, which in this review is termed an elevator alternating-access mechanism. Here, we compare and contrast rocker-switch, rocking-bundle, and elevator alternating-access mechanisms to highlight shared features and novel refinements to the basic alternating-access model.
authors.affiliation: Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; email: ddrew@dbb.su.se.
authors.forename: David
authors.initials: D
authors.lastname: Drew
authors.affiliation: Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065; email: olb2003@med.cornell.edu.
authors.forename: Olga
authors.initials: O
authors.lastname: Boudker
mesh_terms: D001692:Biological Transport; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D015870:Gene Expression; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D013816:Thermodynamics
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins
keywords: alternating-access mechanisms; elevator model; membrane proteins; rocking-bundle model; secondary transporters; structural dynamics