BIOL 4510 Lecture Notes - Diastole, Faraday Constant, Electrochemical Potential
Document Summary
Ion channels are a superfamily of transmembrane proteins that selectively catalyze the flow (movement) of ions across the cell membrane. Their properties include gating (allosteric regulation), selectivity and permeation. Gating refers to the process of channels opening and closing which essentially involves the allosteric regulation of the active site. Permeation is the rate at which an ion can translocate through the channel. Channel are remarkably selective: k+ channels are 10000x more selective for k+ than na+) but still allow over 106 ions to flow per second. Ions cannot diffuse across the lipid membrane due to the high energy barrier (~30 kt). Ion channels allow for the movement of ions across the membrane via a low energy water-filled conduction pathway. Classification of ion channels: voltage-gated channels ligand-gated channels mechanosensitive channels. Ion channels are classified on the basis of: ionic selectivity, functional properties, molecular properties. For example, one of the key ion channels in the heart is the voltage-gated sodium channel.
