To understand the role of Ca 2+ in bacteria, we have predicted and analyzed potential bacterial EF-hand and EFhand like Ca 2+ -binding motifs on a genome-wide scale using our developed bioinformatic tool (http://www.chemistry.gsu. edu/faculty/Yang/Calciomics.htm). A total of 390 putative Ca 2+ -binding proteins have been predicted. Of these, 40 proteins were identified with multiple EF-hands ranging from 2 to 6, and 16 of these 40 proteins have been reported previously [32] . The other 350 proteins contain mononuclear EF-hands. Several examples in three classes of these predictions with diversity in the Ca 2+ -binding loop and flanking structural regions together with one class of prediction from other methods are shown in Table 1 . These proteins are implicated in a variety of cellular activities, including Ca 2+ homeostasis [42] [43] [44] , chemotaxis [8, 45, 46] , binding to scaffold proteins [47] , resistance to acid stress [48, 49] etc. According to their sequence homology and based on the assumption that they evolved from a common ancestor, these proteins could be further classified into several major phylogenetic groups [41] .