SLC8A1
Description
The SLC8A1 (solute carrier family 8 member A1) is a protein-coding gene located on chromosome 2.
The sodium-calcium exchanger (Na+/Ca2+ exchanger, NCX) is an antiporter membrane protein that removes calcium from cells. It uses the energy stored in the electrochemical gradient of sodium (Na+) by allowing Na+ to flow down its gradient across the plasma membrane in exchange for the countertransport of calcium ions (Ca2+). A single calcium ion is exported for the import of three sodium ions. The exchanger exists in many different cell types and animal species. The NCX is considered one of the most important cellular mechanisms for removing Ca2+. The exchanger is usually found in the plasma membranes and the mitochondria and endoplasmic reticulum of excitable cells. The sodium–calcium exchanger is only one of the systems by which the cytoplasmic concentration of calcium ions in the cell is kept low. The exchanger does not bind very tightly to Ca2+ (has a low affinity), but it can transport the ions rapidly (has a high capacity), transporting up to five thousand Ca2+ ions per second. Therefore, it requires large concentrations of Ca2+ to be effective, but is useful for ridding the cell of large amounts of Ca2+ in a short time, as is needed in a neuron after an action potential. Thus, the exchanger also likely plays an important role in regaining the cell's normal calcium concentrations after an excitotoxic insult.
SLC8A1 mediates the exchange of one Ca(2+) ion against three to four Na(+) ions across the cell membrane, contributing to the regulation of cytoplasmic Ca(2+) levels and Ca(2+)-dependent cellular processes (PubMed:1374913, PubMed:11241183, PubMed:1476165). It also plays a role in Ca(2+) transport during excitation-contraction coupling in muscle (PubMed:1374913, PubMed:11241183, PubMed:1476165). During this process, voltage-gated channels initially mediate the rapid increase of cytoplasmic Ca(2+) levels due to the release of Ca(2+) stores from the endoplasmic reticulum (PubMed:1374913, PubMed:11241183, PubMed:1476165). Subsequently, SLC8A1 mediates the export of Ca(2+) from the cell, ensuring the rapid return of cytoplasmic Ca(2+) levels to baseline (PubMed:1374913, PubMed:11241183, PubMed:1476165). SLC8A1 is essential for normal embryonic heart development and the onset of heart contractions (By similarity). {ECO:0000250|UniProtKB:P70414, ECO:0000269|PubMed:11241183, ECO:0000269|PubMed:1374913, ECO:0000269|PubMed:1476165}
SLC8A1 is also known as NCX1.
