NCX-1 is one of three Na+/Ca2+ exchangers (NCX-1, NCX-2, NCX-3) leading to one Ca2+ movement across the plasma membrane in exchange of three Na+ influx. However, the transporter can reverse the direction of the transport if the concentrations of Na+ and Ca2+ change6. The transporter has nine transmembrane domains and intracellular N- and C-terminals. Between tansmembrane domains 5 and 6, the presence of an extra-long intracellular loop, termed the f loop is responsible for regulating the activity of NCX-1 via several different mechanisms like ion binding, phosphorylation, etc. The f loop also has sites which undergo alternative splicing
