S100Z is a recently discovered member of the S100 protein family. S100 proteins are small dimeric members of the EF-hand superfamily of Ca(2+) binding proteins thought to participate in mediating intracellular Ca(2+) signals by binding to and thereby regulating target proteins in a Ca(2+)-dependent manner.S100Z is a 99-amino acid protein capable of interacting with another member of the family, S100P.There are differences in the expression level of S100Z mRNA in various tissues. The highest levels were found in spleen and leukocytes. S100Z gene expression appears to be deregulated in some tumor tissues, compared to expression in their normal counterparts Synonyms: Protein S100-Z, S100 calcium-binding protein Z, S100Z, Gm625, S100-zeta