A protein complex composed of S100A8 and S100A9 and capable of limiting Mn(2+) and Zn(2+) availability at sites of infection. Also binds Ca(2+). Expressed and released by neutrophils and epithelial cells, it exhibits broad-spectrum antimicrobial activity attributed to its metal-binding properties. Endogenous ligand of toll-like receptor 4 (TLR4) and of the receptor for advanced glycation end products (RAGE) initiating signal transduction through NF-kappa-B pathways.
calprotectin heterodimer