S100 calcium binding protein Z, also known as S100Z, is 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. There are differences in the expression level of S100Z mRNA in various tissues.