Scientists are now able to "see" a structure that acts as an atomic-size sorter for cells. Without it, many important life functions—nerve signal firing, heartbeat, hormone secretion—could not occur.

They found that for the mutants displaying calcium blocking, one or two calcium ions are located at the bottom of the selectivity filter. They also discovered that magnesium (Mg 2+) and strontium (Sr ...

Potassium channels are responsible for the selective permeation of K⁺ ions across cell membranes. K⁺ ions permeate in single file through the selectivity filter, a narrow pore lined by backbone ...