Related Experiment Video
Updated: Jun 13, 2026

Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time
Published on: March 11, 2021
Single-molecule dynamics of gating in a neurotransmitter transporter homologue
Yongfang Zhao1, Daniel Terry, Lei Shi
1Center for Molecular Recognition, Columbia University College of Physicians and Surgeons, 630 W. 168th, New York, New York 10032, USA.
Abstract:
Neurotransmitter:Na(+) symporters (NSS) remove neurotransmitters from the synapse in a reuptake process that is driven by the Na(+) gradient. Drugs that interfere with this reuptake mechanism, such as cocaine and antidepressants, profoundly influence behaviour and mood. To probe the nature of the conformational changes that are associated with substrate binding and transport, we have developed a single-molecule fluorescence imaging assay and combined it with functional and computational studies of the prokaryotic NSS homologue LeuT. Here we show molecular details of the modulation of intracellular gating of LeuT by substrates and inhibitors, as well as by mutations that alter binding, transport or both. Our direct observations of single-molecule transitions, reflecting structural dynamics of the intracellular region of the transporter that might be masked by ensemble averaging or suppressed under crystallographic conditions, are interpreted in the context of an allosteric mechanism that couples ion and substrate binding to transport.
Related Concept Videos
Ligand-Gated Ion Channel Receptor: Gating Mechanism
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Non-gated Ion Channels
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Non-gated Ion Channels
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Secondary Active Transport
Secondary Active Transport

