Properties of Calcium Pumping ATPase

描述（由申请人提供）：将继续研究质膜钙离子泵送atp酶的特性。这些钙离子泵存在于心脏、平滑肌、肾、脑、肠上皮、红细胞和许多其他细胞的质膜中。它们参与控制各种细胞的胞内游离钙水平，并参与钙离子跨细胞层（如肠和肾小管上皮）的运动。因此，关于这些泵调节的信息可能提供与高血压和肾脏疾病相关的信息，以及其他疾病。

DESCRIPTION (provided by applicant): Studies on the properties of the calcium ion pumping ATPase of plasma membranes will be continued. These calcium ion pumps exist in the plasma membranes of heart, smooth muscle, kidney, brain, intestinal epithelium, erythrocyte and many other cell types. They are involved in control of intracellular free calcium levels in cells of all kinds, and in movement of calcium ions across cell layers such as the intestinal and kidney tubule epithelia. Information about the regulation of these pumps may thus give information relevant to hypertension and kidney disease, among other conditions. The pump consists of a single polypeptide chain of molecular weight 127,000-137,000 (the exact molecular weight depends on the isoform). Four genes encode different isoforms, and additional forms are created by alternate splices. We have succeeded in expressing this pump in COS and insect cells and have developed assay systems for determining the activity of the expressed enzyme, its binding of calmodulin and of calcium ions. We propose studies designed to extend our knowledge of the function of the different isoforms of this enzyme, and of the calmodulin-binding and calcium ion-binding residues. We will make measurements of the nitrophenyl phosphatase activity, of the rates of the activation of the pump and of the binding of calmodulin. Measurements will also be made to observe the memory of the pump for its previous history of calcium ion exposure. These measurements will be made on appropriately altered forms of the pump and on the different isoforms.