Ion Transport by Single Receptor Channels

Excerpt

Many functions of living cells depend on supramolecular structures that appear in the electron microscope as cell membranes separating the cell interior from the extracellular space. The backbone of the cell membrane is a bimolecular lipid lamella that, because of its insulation properties, provides the basis for selective ion transport processes across the membrane. Ion transport is mediated by so-called transport proteins. These are integral membrane proteins spanning the lipid bilayer.

Excitable cells like nerve cells, muscle fibers, and secretory cells are characterized by a class of transport proteins designated as channel or pore proteins. They have as a common feature that in response to a change in their environment, such as the increase in concentration of a chemical or a change in membrane voltage, they alter their structure. Small cations or anions can then flow down their electrochemical gradient across the membrane via the pores formed by these proteins....