This is a family of sodium/calcium exchanger integral membraneproteins. This family covers the integral membrane regions ofthe proteins. Sodium/calcium exchangers regulate intracellularCa2+ concentrations in many cells; cardiac myocytes, epithelialcells, neurons retinal rod photoreceptors and smooth musclecells [2]. Ca2+ is moved into or out of the cytosol depending onNa+ concentration [2]. In humans and rats there are 3 isoforms;NCX1 NCX2 and NCX3 [1] see Swiss:Q01728, Swiss:P48768 andSwiss:P70549 respectively.