Wild-type Structure of Lactose Permease

Experimental Data Snapshot

  • Resolution: 3.60 Å
  • R-Value Free: 0.333 
  • R-Value Work: 0.294 
  • R-Value Observed: 0.294 

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This is version 1.2 of the entry. See complete history


Structural Determination of Wild-Type Lactose Permease.

Guan, L.Mirza, O.Verner, G.Iwata, S.Kaback, H.R.

(2007) Proc Natl Acad Sci U S A 104: 15294

  • DOI: https://doi.org/10.1073/pnas.0707688104
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Here we describe an x-ray structure of wild-type lactose permease (LacY) from Escherichia coli determined by manipulating phospholipid content during crystallization. The structure exhibits the same global fold as the previous x-ray structures of a mutant that binds sugar but cannot catalyze translocation across the membrane. LacY is organized into two six-helix bundles with twofold pseudosymmetry separated by a large interior hydrophilic cavity open only to the cytoplasmic side and containing the side chains important for sugar and H(+) binding. To initiate transport, binding of sugar and/or an H(+) electrochemical gradient increases the probability of opening on the periplasmic side. Because the inward-facing conformation represents the lowest free-energy state, the rate-limiting step for transport may be the conformational change leading to the outward-facing conformation.

  • Organizational Affiliation

    Department of Physiology, University of California, Los Angeles, CA 90095-1662, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
417Escherichia coliMutation(s): 0 
Membrane Entity: Yes 
Find proteins for P02920 (Escherichia coli (strain K12))
Explore P02920 
Go to UniProtKB:  P02920
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02920
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.60 Å
  • R-Value Free: 0.333 
  • R-Value Work: 0.294 
  • R-Value Observed: 0.294 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 101.37α = 90
b = 127.4β = 90
c = 188.46γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-09-11
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance