|S100/ICaBP type calcium binding domain|
Structure of the S100B protein. Based on PyMOL rendering of PDB 1b4c.
The S100 proteins are a family of low-molecular-weight proteins found in vertebrates and characterized by two calcium-binding sites that have helix-loop-helix ("EF-hand type") conformation. There are at least 21 different S100 proteins. They are encoded by a family of genes whose symbols use the S100 prefix, for example, S100A1, S100A2, S100A3. They are also considered as Damage-associated molecular pattern molecules (DAMPs)
Most S100 proteins are homodimeric, consisting of two identical polypeptides, which are held together by non-covalent bonds. S100 proteins are structurally similar to calmodulin. On the other hand they differ from calmodulin on the other features. For instance, their expression pattern is cell-specific, i.e. they are expressed in particular cell types. Their expression depends on environmental factors. To contrast, calmodulin is a ubiquitous and universal intracellular Ca2+ receptor widely expressed in many cells.
S100 proteins are normally present in cells derived from the neural crest (Schwann cells, and melanocytes), chondrocytes, adipocytes, myoepithelial cells, macrophages, Langerhans cells, dendritic cells, and keratinocytes. It may be present in some breast epithelial cells.
S100 proteins have been implicated in a variety of intracellular and extracellular functions. S100 proteins are involved in regulation of protein phosphorylation, transcription factors, Ca2+ homeostasis, the dynamics of cytoskeleton constituents, enzyme activities, cell growth and differentiation, and the inflammatory response. S100A7 (psoriasin) and S100A15 have been found to act as cytokines in inflammation, particularly in autoimmune skin conditions such as psoriasis.
Several members of the S100 protein family are useful as markers for certain tumors and epidermal differentiation. It can be found in melanomas, 100% of schwannomas, 100% of neurofibromas (weaker than schwannomas), 50% of malignant peripheral nerve sheath tumors (may be weak and/or focal), paraganglioma stromal cells, histiocytoma and clear cell sarcomas. Further, S100 proteins are markers for inflammatory diseases and can mediate inflammation and act as antimicrobials.
S100 proteins have been used in the lab as cell markers for anatomic pathology.
- S100A1, S100A2, S100A3, S100A4, S100A5, S100A6, S100A7 (psoriasin), S100A8 (calgranulin A), S100A9 (calgranulin B), S100A10, S100A11, S100A12 (calgranulin C), S100A13, S100A14, S100A15 (koebnerisin), S100A16
- S100Z (S100Z)
The "S100" symbol prefix is derived from the fact that these proteins are soluble in 100%, i.e. saturated, ammonium sulfate at neutral pH. The symbol has often been hyphenated, but current gene and protein nomenclature, such as HGNC nomenclature, does not use hyphens in symbols.
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- Wilson, AJ; Maddox, PH; Jenkins, D (January 1991). "CD1a and S100 antigen expression in skin Langerhans cells in patients with breast cancer.". The Journal of pathology 163 (1): 25–30. PMID 2002421.
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- Nonaka D, Chiriboga L, Rubin BP (November 2008). "Differential expression of S100 protein subtypes in malignant melanoma, and benign and malignant peripheral nerve sheath tumors". J. Cutan. Pathol. 35 (11): 1014–9. doi:10.1111/j.1600-0560.2007.00953.x. PMID 18547346.
- Wolf R, Ruzicka T, Yuspa SH (July 2010). "Novel S100A7 (psoriasin)/S100A15 (koebnerisin) subfamily: highly homologous but distinct in regulation and function". Amino Acids 41 (4): 789–96. doi:10.1007/s00726-010-0666-4. PMID 20596736.
- Elsevier, Dorland's Illustrated Medical Dictionary, Elsevier.
- Wolf R, Voscopoulos CJ, FitzGerald PC, et al. (2006). "The mouse S100A15 ortholog parallels genomic organization, structure, gene expression, and protein-processing pattern of the human S100A7/A15 subfamily during epidermal maturation". J. Invest. Dermatol. 126 (7): 1600–8. doi:10.1038/sj.jid.5700210. PMID 16528363.
- Ronald Wolf, O. M. Zack Howard, Hui-Fang Dong, Christopher Voscopoulos, Karen Boeshans, Jason Winston, Rao Divi, Michele Gunsior, Paul Goldsmith, Bijan Ahvazi, Triantafyllos Chavakis, Joost J. Oppenheim and Stuart H. Yuspa (2010). "Chemotactic Activity of S100A7 (Psoriasin) Is Mediated by the Receptor for Advanced Glycation End Products and Potentiates Inflammation with Highly Homologous but Functionally Distinct S100A15.". The Journal of Immunology 181 (2): 1499–1506.
- Ronald Wolf, Christopher Voscopoulos, Jason Winston, Alif Dharamsi, Paul Goldsmith Michele Gunsior, Barbara K. Vonderhaar, Melanie Olson, Peter H. Watson, and Stuart H. Yuspa. (2008). "Highly homologous hS100A15 and hS100A7 proteins are distinctly expressed in normal breast tissue and breast cancer.". J. Cancer Lett. 277 (1): 101–107. doi:10.1016/j.canlet.2008.11.032. PMC 2680177. PMID 19136201.
- Ronald Wolf, Francesca Mascia, Alif Dharamsi, O. M. Zack Howard, Christophe Cataisson, Val Bliskovski, Jason Winston, Lionel Feigenbaum, Ulrike Lichti, Thomas Ruzicka Triantafyllos Chavakis, and Stuart H. Yuspa. (2010). "Gene from a Psoriasis Susceptibility Locus Primes the Skin for Inflammation.". Science Translational Medicine 2 (61): 61ra90. doi:10.1126/scitranslmed.3001108. PMID 21148126.