Calmodulin and the calmodulin-like domain protein kinases (CDPKs) are the most widely distributed EF-hand Ca²⁺-binding proteins in plants, and serve as the primary receptors for second messenger Ca²⁺signals (1). Calmodulin is the primary nonenzymatic Ca²⁺-binding protein in plants, and is the subject of interest because a growing number of the targets of calmodulin regulation in plants are not identical to those found in animals and yeast (2). Two features that complicate the study of calmodulins extracted directly from higher plant tissues, however, is the relatively low yield of protein per unit mass of tissue compared with yields obtained from most animal tissues, and the overlapping patterns of expression of multiple isoforms of the protein. For example, Arabidopsis thaliana, the genetically simplest higher plant, possesses at least 10 calmodulin genes encoding a family of seven protein isoforms (2,3).