Calcium channel
A calcium channel is an ion channel which shows selective permeability to calcium ions. It is sometimes synonymous with voltage-gated calcium channel,[1] which are a type of calcium channel regulated by changes in membrane potential. Some calcium channels are regulated by the binding of a ligand.[2][3] Other calcium channels can also be regulated by both voltage and ligands to provide precise control over ion flow. Some cation channels allow calcium as well as other cations to pass through the membrane.
Calcium channels can participate in the creation of action potentials across cell membranes. Calcium channels can also be used to release calcium ions as second messengers within the cell, affecting downstream signaling pathways.
Non-selective Channels Permeable to Calcium[edit]
There are several cation channel families that allow positively charged ions including calcium to pass through. These include P2X receptors, Transient Receptor Potential (TRP) channels, Cyclic nucleotide-gated (CNG) channels, Acid-sensing ion channels, and SOC channels.[8] These channels can be regulated by membrane voltage potentials, ligands, and/or other cellular conditions. Cat-Sper channels, found in mammalian sperm, are one example of this as they are voltage gated and ligand regulated.[9]