The Alternating Access Transport Mechanism in LacY
- Author(s): Kaback, H. Ronald
- Smirnova, Irina
- Kasho, Vladimir
- Nie, Yiling
- Zhou, Yonggang
- et al.
Published Web Locationhttps://doi.org/10.1007/s00232-010-9327-5
Lactose permease of Escherichia coli (LacY) is highly dynamic, and sugar binding causes closing of a large inward-facing cavity with opening of a wide outward-facing hydrophilic cavity. Therefore, lactose/H+ symport via LacY very likely involves a global conformational change that allows alternating access of single sugar- and H+-binding sites to either side of the membrane. Here, in honor of Stephan H. White’s seventieth birthday, we review in camera the various biochemical/biophysical approaches that provide experimental evidence for the alternating access mechanism.