PMID:21254783

Citation	Jiang, X, Nie, Y and Kaback, HR (2011) Site-directed alkylation studies with LacY provide evidence for the alternating access model of transport. Biochemistry 50:1634-40
Abstract	In total, 59 single Cys-replacement mutants in helix VII and helix X of the lactose permease of Escherichia coli were subjected to site-directed fluorescence labeling in right-side-out membrane vesicles to complete the testing of Cys accessibility or reactivity. For both helices, accessibility/reactivity is relatively low at the level of the sugar-binding site where the helices are tightly packed. However, labeling of Cys substitutions in helix VII with tetramethylrhodamine-5-maleimide decreases from the middle toward the cytoplasmic end and increases toward the periplasmic end. Helix X is labeled mainly on the side facing the central hydrophilic cavity with relatively small or no changes in the presence of ligand. In contrast, sugar binding causes a significant increase in accessibility/reactivity at the periplasmic end of helix VII. When considered with similar findings from N-ethylmaleimide alkylation studies, the results confirm and extend support for the alternating access model.
Links	PubMed PMC3057939 Online version:10.1021/bi101988s
Keywords	Alkylation; Biological Transport; Klebsiella pneumoniae/enzymology; Membrane Transport Proteins/chemistry; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism; Models, Biological; Models, Molecular; Mutation; Protein Structure, Tertiary
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status

References

See Help:References for how to manage references in GONUTS.