2-((methylsulfonyl)thio)ethyl (N-(N,N-dimethylamino)ethyl)carbamate

MTS-AC-treated channels showed a pattern of steps in the single channel current recordings on the time scale of the carbamate bond isomerization. The pattern and the size of these steps was sensitive to the location of the thiol-reactive site in relation to the channel entrance. Thus, MTS-AC may prove useful as a reagent for establishing proximity to the pore in studies of ion channel proteins of unknown structure.