[Na+ -Ca2+ exchanger].

Na+ -Ca2+ exchanger couples the translocation of Na+ in one direction with that of Ca2+ in the opposite direction, and it is considered to have an important role in Ca2+ homeostasis in several cells. There are two types of Na+ -Ca2+ exchangers (cardiac and rod outer segment types). The cardiac clone (NCX1) is modeled to have an amino-terminal cleaved signal sequence, 11 transmembrane segments, and a large hydrophilic cytoplasmic domain. Several isoforms generated by alternative splicing of NCX1 and an isoform (NCX2), a product of a different gene, are present in different tissues. This brief review focuses on the physiological importance, molecular aspects and the pathological roles of the exchanger, especially NCX1.