Identification of a novel calcium binding protein from bovine brain

Abstract

A novel Ca'+ binding protein, named caligulin, was extracted from the heat-treated 100000 x g supernatant of bovine brain and purified to electrophoretic homogeneity. The apparent MI of caligulin determined on sodium dodecyl sulfate polyacrylamide gels was 24000. Analysis by gel filtration chromatography indicated an apparent M, of 33000, suggesting a monomeric protein. Amino acid composition data demonstrated the presence of 25% acidic residues, 12% basic residues and 10% leucine. In the presence of 1 mM MgClz and 0.15 M KCl, caligulin bound 1 mol Ca'+/mol protein with halfmaximal binding at about 0.2pM Ca'+.Cd' binding protein Brain