Comparing ion conductance recordings of synthetic lipid bilayers with cell membranes containing TRP channels

TL;DR

This study compares electrical conductance events from TRP channels in cell membranes with synthetic lipid membranes near phase transitions, revealing similar channel-like behaviors and complex conductance patterns in both systems.

Contribution

It demonstrates that synthetic lipid membranes can mimic many electrical phenomena of protein ion channels, highlighting the importance of thermodynamic conditions in channel activity.

Findings

Both systems show unitary currents and flickering behavior.

Conductances and lifetimes are comparable between lipid and protein channels.

Current-voltage relationships are non-linear and asymmetric in both cases.

Abstract

In this article we compare electrical conductance events from single channel recordings of three TRP channel proteins (TRPA1, TRPM2 and TRPM8) expressed in human embryonic kidney cells with channel events recorded on synthetic lipid membranes close to melting transitions. Ion channels from the TRP family are involved in a variety of sensory processes including thermo- and mechano-reception. Synthetic lipid membranes close to phase transitions display channel-like events that respond to stimuli related to changes in intensive thermodynamic variables such as pressure and temperature. TRP channel activity is characterized by typical patterns of current events dependent on the type of protein expressed. Synthetic lipid bilayers show a wide spectrum of electrical phenomena that are considered typical for the activity of protein ion channels. We find unitary currents, burst behavior, flickering, multistep-conductances, and spikes behavior in both preparations. Moreover, we report conductances and lifetimes for lipid channels as described for protein channels. Non-linear and asymmetric current-voltage relationships are seen in both systems. Without further knowledge of the recording conditions, no easy decision can be made whether short current traces originate from a channel protein or from a pure lipid membrane