S100A11 (S100C, Calgizzarin) is a member of the S100 family of EF-hand Ca2+-binding proteins, which is expressed in smooth muscle and other tissues. It is also localized in the cytoplasm in resting cells and moves to the cell periphery in cultured epidermal keratinocytes following calcium challenge. This movement requires the presence of intact microtubules.
S100A11 was shown to bind to annexin A1 and the S100A11/annexin I complex is a heterotetramer consisting of two S100A11 and two annexin I proteins. Ca2+ binding to S100A11 induces a conformational change that exposes a hydrophobic surface for interaction with target proteins. S100A11 was also shown to interact with annexin A6 in Ca2+-dependent manner.