A key component in the design of artificial ion channels is the design of regulatory elements. We have synthesized a derivative of the peptide ion channel, gramicidin, in which an amino group is connected to the mouth of the channel by a Linker containing a carbamate group. Thermal cis-trans isomerization of the carbamate, which can be detected at the single-molecule level, is found to regulate the flux of Cs+ ions through the channel. The predictability of the system suggests that design of more sophisticated types of channel regulation will be possible.