S100A4 is a member of the S100 family of proteins. The S100 family is further classified as a member of the EF-hand superfamily of Ca++-binding proteins. These participate in both calcium-dependent and calcium-independent protein-protein interactions. The hallmark of this superfamily is the EF-hand motif that consists of a Ca++-binding site flanked by two α-helices (helix E and helix F) that were originally identified in a right-handed model of carp muscle calcium-binding protein. Mouse S100A4 is 101 amino acids (aa) in length. It contains two EF hand domains, one between aa 12-47, and a second between aa 50-85. S100A4 activity has been associated with cell transformation. It seems likely this is either coincidental, or a consequence, rather than a cause of transformation.
