The lactose permease of Escherichia coli: overall structure, the sugar‐binding site and the alternating access model for transport

FEBS Letters

Kasho, Vladimir²  Iwata, So¹  Kaback, H.Ronald²  Smirnova, Irina²  Abramson, Jeff¹  Verner, Gillian² 

[1] Department of Biological Sciences, Imperial College London, London SW7 2AZ, UK;Howard Hughes Medical Institute, Departments of Physiology and Microbiology, Immunology, and Molecular Genetics, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA

关键词: Transport;    Bioenergetics;    Membrane protein structure;    Sugar-binding site;    Alternating accessibility;   

DOI  :  10.1016/S0014-5793(03)01087-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Membrane transport proteins transduce free energy stored in electrochemical ion gradients into a concentration gradient and are a major class of membrane proteins, many of which play important roles in human health and disease. Recently, the X-ray structure of the Escherichia coli lactose permease (LacY), an intensively studied member of a large group of related membrane transport proteins, was solved at 3.5 Å. LacY is composed of N- and C-terminal domains, each with six transmembrane helices, symmetrically positioned within the molecule. The structure represents the inward-facing conformation, as evidenced by a large internal hydrophilic cavity open to the cytoplasmic side. The structure with a bound lactose homolog reveals the sugar-binding site in the cavity, and a mechanism for translocation across the membrane is proposed in which the sugar-binding site has alternating accessibility to either side of the membrane.

【 授权许可】

Unknown