Many intracellular processes have been shown to be regulated by Ca2+, presumably via its interaction with specific Ca2+- dependent regulatory proteins. We have recently described the purification of members of a novel family of Ca2+-binding proteins called calelectrins and have shown that one of these proteins, the 32.5 kDa calelectrin, is highly expressed primarily in ductal epithelial cells of various organs and the cardiac intercalated disk. In contrast, the 67 kDa calelectrin, another member of this protein family, is ubiquitously expressed. Several lines of evidence suggest that the calelectrin-like Ca2+-binding proteins may be involved in signal-dependent phospholipid metabolism, such as arachidonic acid or phosphoinositol release, and/or in the regulation of membrane traffic. Here, we propose to purify biochemical amounts of several members of the calelectrin Ca2+-binding protein family, to clone their cDNAs and to deduce their amino acid sequences. The purified proteins will be used to obtain affinity-purified antisera and monoclonal antibodies for immunocytochemistry and inhibition experiments, and to test various biochemical hypotheses concerning the functions of the calelectrins in arachidonic acid and phosphatidylinositol metabolism and membrane traffic. These experiments will yield insight into the functional and evolutionary relationships and regulatory roles of these proteins. This information in turn will help guide our future studies which will investigate the role of calelectrins in disease states such as cystic fibrosis and certain cardiomyopathies.
