Identification of bovine brain Ca2+-binding proteins.

In a previous communication (Waisman, D.M., Smallwood, J.I., Lafreniere, D. and Rasmussen, H. (1983) Biochem, Biophys. Res. Commun. 116, 435-441) we reported that chromatography of bovine brain 100,000 X g supernatant on diethylaminoethyl (DEAE) cellulose and analysis of resultant fractions by chelex competitive calcium binding assay, resolved three peaks of calcium binding activity. Gel permeation chromatographic analysis of each peak resolved apparent Mr 40,000 (Peak I), Mr 75,000, Mr 230,000 and Mr 420,000 (Peak II), and Mr 38,000 (Peak III). In the present communication the calcium binding proteins responsible for the calcium binding activity peaks resolved by gel permeation chromatography, have been purified and identified as caligulin, (Mr 40,000), calcineurin, (Mr 230,000) and calmodulin, (Mr 38,000). In addition, a novel calcium binding protein (Mr 48,000 by SDS PAGE) has been identified from the Mr 75,000 calcium binding activity peak.