Ion Channels

Abstract

Ion channels catalyze the transmembrane movement of small inorganic ions across biological membranes. They do so by forming continuous, hydrophilic pores through which ions can cross the barrier imposed by the lipid bilayer hydrophobic core. Ion channels serve many functions: they underlie the changes in membrane potential that control many cell functions, including the propagated electrical signaling (the action potentials) in electrically excitable cells; they allow for the bulk movement of ions across cell membranes. In this article we summarize key features of ion channels, with special emphasis on the channels in the plasma membrane—their structure and catalytic power, the generation of membrane potential changes, the regulation (or gating) that underlies normal channel function, and how channel function can be modulated by small molecules.

Temporary Membrane Permeabilization via the Pore-Forming Toxin Lysenin

“…In addition to allowing the passage of relatively large molecules [8][9][10]15,16], the potential modulation of the membrane permeability through intrinsic regulatory mechanisms might provide unique controls of the barrier function previously difficult to attain by alternative techniques. As an example, ion channels present high transport rate, selectivity, and regulation [17][18][19]; with a few notable exceptions [2], their narrow opening and high selectivity limit their applicability to intracellular delivery of specific, small-sized ions and compounds. Scientists have utilized pore-forming toxins (PFTs) as alternative pathways for intracellular delivery, which generally have a larger diameter and may allow passage of larger molecules, to address this shortcoming [8][9][10]14,16,20].…”