Ion channels are formed by proteins with multiple, usually six, transmembrane domains, which as homo- or hetero-oligomers form aqueous pores that allow ions to pass between the outside and the inside of the cell according to their concentration gradient. Ion channels thus conduct ion currents in response to changes in membrane voltage (voltage-gated ion channels) or after binding of ligands (ligand gated). The latter applies to neurotransmitters binding at extracellular sites and to second messengers binding at intracellular sites of the channel oligomers. In the following, we discuss how the membrane potential is maintained and explain the molecular architecture and function of several ion channels. As an example, we elucidate, how voltage- and ligand-gated ion channels work together at the neuromuscular junction and at synapses. Finally, we briefly introduce the large family of “transient receptor potential” (TRP) ion channels.
- Shen H, Zhou Q, Pan X, Li Z, Wu J, Yan N (2017) Structure of a eukaryotic voltage-gated sodium channel at near-atomic resolution. Science 355:1Google Scholar