Ion Channels
Pore-forming transmembrane proteins that allow selective passive passage of specific ions down their electrochemical gradient.
Governing formula
I_channel = g_channel (V_m - E_ion)
SI unit
pS (Picosiemens Conductance) & pA (Current)
In depth
Ion channels feature narrow selectivity filters (discriminating K⁺, Na⁺, Ca²⁺, Cl⁻) and gating mechanisms controlled by membrane voltage, chemical ligands, or mechanical strain.
Examples in the real world
Voltage-gated sodium channels opening rapidly during neuron action potential initiation.