CALMODULIN AND CALMODULIN-BINDING PROTEINS IN PLANTS

Calmodulin is a small Ca2+-binding protein that acts to transduce seco nd messenger signals into a wide array of cellular responses. Plant ca lmodulins share many structural and functional features with their hom ologs from animals and yeast, but the expression of multiple protein i soforms appears to be a distinctive feature of higher plants. Calmodul in acts by binding to short peptide sequences within target proteins, thereby inducing structural changes, which alters their activities in response to changes in intracellular Ca2+ concentration. The spectrum of plant calmodulin-binding proteins shares some overlap with that fou nd in animals, but a growing number of calmodulin-regulated proteins i n plants appear to be unique. Ca2+-binding and enzymatic activation pr operties of calmodulin are discussed emphasizing the functional linkag es between these processes and the diverse pathways that are dependent on Ca2+ signaling.