The S100 proteins are a family of low molecular-weight
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...
s found in
vertebrate
Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...
s characterized by two
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...
-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
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s 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 Ca
2+ 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,
adipocyte
Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat. Adipocytes are derived from mesenchymal stem cells which give rise to adipocytes through adipogenesi ...
s,
myoepithelial cells,
macrophages,
Langerhans cell
A Langerhans cell (LC) is a tissue-resident macrophage of the skin. These cells contain organelles called Birbeck granules. They are present in all layers of the epidermis and are most prominent in the stratum spinosum. They also occur in th ...
s,
, and
keratinocytes. They may be present in some
breast
The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues.
In females, it serves as the mammary gland, which produces and s ...
epithelial cells.
S100 proteins have been implicated in a variety of intracellular and extracellular functions,
such as regulation of protein phosphorylation, transcription factors, Ca
2+ 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), ''
S100A8'' (calgranulin A), ''
S100A9'' (calgranulin B), ''
S100A10,
S100A11,
S100A12'' (calgranulin C), ''
S100A13,
S100A14
S100 calcium binding protein A14 (S100A14) is a protein that in humans is encoded by the S100A14 gene.
Function
This gene encodes a member of the S100 protein family which contains an EF-hand motif and binds calcium. The gene is located i ...
,
S100A15 ''(koebnerisin), ''
S100A16
S100 calcium-binding protein A16 (S100A16) is a protein that in humans is encoded by the ''S100A16'' gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." mean ...
''
* ''
S100B
* ''
S100P
* ''
S100Z S1, S01, S.I, S-1, S.1, Š-1 or S 1 may refer to:
Biology and chemistry
* S1 nuclease, an enzyme that digests singled-stranded DNA and RNA
* S1: Keep locked up, a safety phrase in chemistry
* Primary somatosensory cortex, also known as S1
* Tega ...
'' (), ''
CRNN;
FLG, FLG2,
HRNR,
RPTN,
S100G,
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
*
*
Calprotectin
References
Further reading
*
*
*
*
External links
*
{{Portal bar, Biology
Diagnostic neurology
Protein families