The overall aim of this project is to investigate the role of the plasma membrane Ca2+ pump in Ca2+ transport in kidney, particularly the kidneys of rat. Both monoclonal antibodies and gene cloning techniques (polymerase chain reaction) will be used to explore the expression of different isozymes along the tubule. It is likely that the Ca2+ pump has multiple roles in the nephron, including its involvement in control of intracellular Ca2+ signalling and its role in transcellular transport of Ca2+ (by means of which the kidney recaptures Ca2+ from the urine). Different isozymes of the Ca2+ pump are likely to be involved in different roles, and probably differ from one another in properties such as calcium affinity, regulation by protein kinases and sensitivity to calmodulin. Determination of the distribution of Ca2+ pump isoforms along the nephron will provide fundamental knowledge needed to understand renal handling of calcium in health and disease.