Localization of Ca(2+)-binding proteins of rat cortex on two-dimensional gels-I. Identification of calmodulin and the b subunit of calcineurin.

At least three Ca(2+)-binding proteins were detected in rat cortex by (45)Ca(2+) autoradiography of two-dimensional electrophoretograms. The identities of two of these Ca(2+)-binding proteins were determined to be calmodulin and the B subunit of calcineurin. The identification was based upon the following criteria: (1) co-localization on polyacrylamide gels with the appropriate purified proteins, (2) staining of nitrocellulose blots with specific antisera for calmodulin and calcineurin and (3) ability to bind Ca(2+). This information is useful in that it identifies two major brain proteins visible on silver-stained two-dimensional polyacrylamide gels. In addition, this data reveals the location of an unidentified Ca(2+)-binding protein of molecular weight ? 18,000 Da and pI 5.4 on these gels.