An ion transporter is a type of protein found in cell membranes that helps move ions, such as sodium, potassium, and calcium, across the membrane. This movement is essential for various cellular functions, including maintaining the cell's electrical charge and regulating fluid balance. Ion transporters can work through active transport, which requires energy, or passive transport, which does not. These transporters play a crucial role in processes like nerve signal transmission and muscle contraction. By controlling the concentration of ions inside and outside the cell, ion transporters help ensure that cells function properly and respond to changes in their environment.