biology

S100 protein

S100 protein is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand S100 protein rather than just read about it. In short: The S100 proteins are a family of low molecular-weight proteins found in vertebrates characterized by two calcium-binding sites that have helix-loop-helix ("EF-hand-type") conformation. At least 21 different S100 proteins are known.

Key takeaways

S100 protein belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect S100 protein to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of S100 protein from memory before moving on to harder problems.

Reference excerpt

The S100 proteins are a family of low molecular-weight proteins found in vertebrates characterized by two calcium-binding sites that have helix-loop-helix ("EF-hand-type") conformation. At least 21 different S100 proteins are known. 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), and knockdown of aryl hydrocarbon receptor downregulates the expression of S100 proteins in THP-1 cells.

Structure Most S100 proteins consist of two identical polypeptides (homodimeric), which are held together by noncovalent bonds. They are structurally similar to calmodulin. They differ from calmodulin, though, 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. In contrast, calmodulin is a ubiquitous and universal intracellular Ca2+ receptor widely expressed in many cells.

Normal function 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. They may be present in some breast epithelial cells. S100 proteins have been implicated in a variety of intracellular and extracellular functions, such as 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.

Pathology

Several members of the S100 protein family are useful as markers for certain tumors and epidermal differentiation. They 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.

Human genes S100A1, S100A2, S100A3, S100A4, S100A5, S100A6, S100A7 (psoriasin), S100A7A (koebnerisin), S100A8 (calgranulin A), S100A9 (calgranulin B), S100A10, S100A11, S100A12 (calgranulin C), S100A13, S100A14, S100A16 S100B, S100G, S100P, S100Z (S100Z) CRNN, FLG, FLG2, HRNR, RPTN, TCHH, THHL1

Nomenclature The "S100" symbol prefix denotes 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 HUGO Gene Nomenclature Committee nomenclature, does not use hyphens in symbols.

See also List of histologic stains that aid in diagnosis of cutaneous conditions Calprotectin

References

Further reading Wolf R, Voscopoulos CJ, FitzGerald PC, Goldsmith P, Cataisson C, Gunsior M, Walz M, Ruzicka T, Yuspa SH (2006). "The mouse S100A15 ortholog parallels genomic organization, structure, gene expression, and protein-processing pattern of the human S100A7/A15 subfamily during epidermal maturation". The Journal of Investigative Dermatology. 126 (7): 1600–8. doi:10.1038/sj.jid.5700210. PMID 16528363. Wolf R, Howard OM, Dong HF, Voscopoulos C, Boeshans K, Winston J, Divi R, Gunsior M, Goldsmith P, Ahvazi B, Chavakis T, Oppenheim JJ, Yuspa SH (2008). "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". Journal of Immunology. 181 (2): 1499–506. doi:10.4049/jimmunol.181.2.1499. PMC 2435511. PMID 18606705. Wolf R, Voscopoulos C, Winston J, Dharamsi A, Goldsmith P, Gunsior M, Vonderhaar BK, Olson M, Watson PH, Yuspa SH (2009). "Highly homologous hS100A15 and hS100A7 proteins are distinctly expressed in normal breast tissue and breast cancer". Cancer Letters. 277 (1): 101–7. doi:10.1016/j.canlet.2008.11.032. PMC 2680177. PMID 19136201. Wolf R, Mascia F, Dharamsi A, Howard OM, Cataisson C, Bliskovski V, Winston J, Feigenbaum L, Lichti U, Ruzicka T, Chavakis T, Yuspa SH (2010). "Gene from a psoriasis susceptibility locus primes the skin for inflammation". Science Translational Medicine. 2 (61): 61ra90. doi:10.1126/scitranslmed.3001108. PMC 6334290. PMID 21148126.

External links S100+Proteins at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Illustrations

Worked examples

Example 1 — a first encounter with S100 protein

Start with the simplest possible case. Write down what S100 protein claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to S100 protein before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about S100 protein ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of S100 protein

In research: S100 protein appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses S100 protein in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: S100 protein is common in secondary-school and first-year university syllabi. It links to neighbouring topics Diagnostic neurology, Protein families, S100 proteins, so understanding it makes those chapters shorter.
In everyday life: Look for S100 protein outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study S100 protein in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what S100 protein means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain S100 protein out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is S100 protein in simple terms?

Why does S100 protein matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study S100 protein?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on S100 protein.