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Membrane transport proteins that transduce free energy stored in electrochemical ion gradients into a concentration gradient are a major class of membrane proteins. We report the crystal structure at 3.5 angstroms of the Escherichia coli lactose permease, an intensively studied member of the major facilitator superfamily of transporters. The molecule is(More)
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(More)
A simplified approach for purification of functional lactose permease from Escherichia coli is described that is based on the construction of chimeras between the permease and a 100-amino acid residue polypeptide containing the biotin acceptor domain from the oxaloacetate decarboxylase of Klebsiella pneumoniae [Cronan, J. E., Jr. (1990) J. Biol. Chem. 265,(More)
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(More)
A novel strategy is presented for the crystallization of membrane proteins or other proteins with low solubility and/or stability. The method is illustrated with the lactose permease from Escherichia coli, in which a fusion is constructed between the permease and a 'carrier' protein. The carrier is a soluble, stable protein with its C and N termini close(More)
Integration of biochemical and biophysical data on the lactose permease of Escherichia coli has culminated in a molecular model that predicts substrate-protein proximities which include interaction of a hydroxyl group in the galactopyranosyl ring with Glu269. In order to test this hypothesis, we studied covalent modification of carboxyl groups with(More)
The effect of light on the biosynthesis and the assembly of rod photoreceptor outer segment membranes was analyzed in vitro using retinas from Xenopus laevis. The number of open discs at the base of the outer segment was used as a morphologic index to evaluate relative differences in rates of membrane assembly. Assembly was stimulated in vitro by light, as(More)
Isolated retinas from Xenopus laevis tadpoles or juvenile frogs were incubated in Ringer's bicarbonate-glucose medium in which sodium chloride was replaced with equimolar amounts of either sodium aspartate (NaAsp) or sodium glutamate (NaGlu). At all concentrations tested (0.1 to 50 mM), both acidic amino acids caused a dramatic decrease in the incorporation(More)
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