Format

Send to

Choose Destination
FEBS Lett. 2003 Nov 27;555(1):96-101.

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

Author information

1
Department of Biological Sciences, Imperial College London, London SW7 2AZ, UK.

Abstract

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 A. 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.

PMID:
14630326
DOI:
10.1016/s0014-5793(03)01087-1
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center