https://phys.org/news/2018-07-fueling.html

Reporting last month in the Proceedings of the National Academy of Sciences, Hassane Mchaourab, PhD, and colleagues used DEER (double-electron electron resonance) spectroscopy to show how some conserved amino acid residues in NorM, a MATE transporter from the cholera pathogen, mediate the structural changes involved in drug efflux.

By measuring distances between spin labels in NorM, they found that a network of residues in the N-terminal domain is critical for ion-dependent conformational changes, while residues in the C-terminal domain mediate drug binding.