Ionkanal

An ion channel is a protein that acts as a pore in a cell membrane, allowing specific ions to pass through. These channels are crucial for many physiological processes, including nerve impulse transmission, muscle contraction, and maintaining cell volume. They are typically composed of multiple protein subunits that assemble to form a central pore. The selectivity of an ion channel, meaning which ions it allows to pass, is determined by the amino acid residues lining the pore. These residues can create a filter that favors certain ions based on their size, charge, and hydration shell.

Ion channels can be classified based on how they are regulated. Voltage-gated channels open or close in response to changes in the electrical potential across the cell membrane. Ligand-gated channels open or close when a specific molecule, such as a neurotransmitter, binds to them. Mechanically gated channels respond to physical forces. Some channels are also regulated by intracellular signaling molecules or by temperature. The flow of ions through these channels creates electrical currents that are fundamental to cellular function. Disruptions in ion channel function can lead to various diseases, including epilepsy, cystic fibrosis, and cardiac arrhythmias.