S100 calcium-binding protein A7 (S100A7)

S100 calcium-binding protein A7 (S100A7), also known as psoriasin, is a small EF-hand type calcium-binding protein with a molecular weight of approximately 11.4 kDa. It is primarily expressed in keratinocytes of the epidermis and is dramatically upregulated in psoriatic lesions. Structurally, it forms a symmetric homodimer stabilized by zinc ions and contains both canonical and non-canonical EF-hand domains for metal ion binding. Unlike most S100 proteins, its N-terminal EF-hand motif does not bind Ca²⁺ due to specific amino acid substitutions; however, it can bind zinc via a distinct site. Functionally, S100A7 participates in various intra-and extracellular processes including regulation of cell growth/differentiation/apoptosis; immune responses; antimicrobial defense through metal sequestration; chemotaxis; inflammation signaling—often via interaction with the receptor for advanced glycation end products (RAGE), which activates NF-kB-mediated pro-inflammatory pathways. It acts as a damage-associated molecular pattern molecule during infection or tissue stress. Clinically, elevated expression of S100A7 serves as a biomarker for psoriasis severity/prognosis and has been implicated in promoting aggressive behavior in several cancers by regulating migration/invasion/metastasis/epithelial-mesenchymal transition processes. Its role extends to limiting bacterial infections on the skin surface by depriving pathogens of essential metals like zinc.

Other names

PsoriasinS100A7S100 calcium binding protein A7