Chloride potassium symporter  The potassium chloride symporter is a membrane transport protein that is present in the S3-segment of the renal proximal tubule and in the neuron. It functions in renal chloride reabsorption to transport chloride across the basolateral membrane. The concentrations of K+ and Cl− ions are high inside the cell due to the activities of Na+-K+ pump and NKCC cotransporter, respectively. Hence, their net driving force acting on the K/Cl cotransporter favours the exit of both K+ and Cl− from the cell. They can lower intracellular chloride concentrations below the electrochemical equilibrium potential. They are of solute carrier family 12. Types of chloride potassium symporter are:  Each is encoded by a separate gene. The preceding symporters are other types of ion pumps. Member 3, for instance, is the sodium-chloride symporter.