• Purity

  >95%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured in a cell proliferation assay using human peripheral blood monocytes. The ED    ₅₀ for this effect is 1-4 μg/mL.

• Source

  E. coli-derived Met1-Glu92

• Accession #

• N-terminal Sequence    
  Analysis

  Met1

• Structure / Form

  Monomer

• Predicted Molecular Mass

  10.7 kDa

• SDS-PAGE

  7 kDa, reducing conditions

Background: S100B

S100B, previously called S100 beta, belongs to the S100 family within the EF-hand superfamily of Ca  ²⁺ binding proteins (1-3). S100 proteins contain two EF-hand motifs that differ in affinity, separated by a hinge region with a hydrophobic cleft that is exposed upon Ca  ²⁺ binding (4). S100B is a 91 amino acid (aa) protein, after removal of the initial methionine, and is found as homodimers of 10.4 kDa monomers. Human S100B shares 99%, 98%, 100%, 99% and 97% aa sequence identity with mouse, rat, rabbit, equine and bovine S100B, respectively. Within the S100 family, human S100B shows the highest aa identity (59%) with S100A1. S100B is expressed primarily by astrocytes and oligodendrocytes in the central nervous system, and by Schwann cells in the peripheral nervous system (5). Ca  ²⁺-bound S100B interacts   in vitro with at least 20 cytoplasmic proteins, including several structural molecules such as tubulin and GFAP (1, 4). It can inhibit the phosphorylation of these kinase substrates and others such as tau and neuromodulin (1, 5). Astrocytes can secrete S100B, which then acts in a cytokine-like manner (5, 6). Nanomolar concentrations of S100B are secreted constitutively, promote proliferation, and are neurotrophic and anti-apoptotic (1, 6). Blood levels of S100B reflect extracellular concentrations within the nervous system, and are elevated in Down’s syndrome, Alzheimer’s disease and Tourette’s syndrome, metabolic stress, acute brain injury and brain tumors (5, 7). Micromolar concentrations of S100B can be destructive and pro-apoptotic; they induce the expression of iNOS, COX-2, IL-1, IL‑6 and TNF-alpha by microglia, astrocytes or neurons (6, 8-11). Most extracellular actions of S100B can be mediated by RAGE (receptor for advanced glycation end products), which is also a receptor for other S100 proteins (6, 10, 11).

• References:

1. Michetti, F. et al. (2012) J. Neurochem. 120:644.

2. Marenholz, I. et al. (2004) Biochem. Biophys. Res. Commun. 322:1111.

3. Allore, R.J. et al. (1990) J. Biol. Chem. 265:15537.

4. McClintock, K.A. and G.S. Shaw (2003) J. Biol. Chem. 278:6251.

5. Sen, J. & A. Belli (2007) J. Neurosci. Res. 85:1373.

6. Huttunen, H.J. et al. (2000) J. Biol. Chem. 275:40096.

7. Gerlach, R. et al. (2006) Neuroscience 141:1697.

8. Hu, J. et al. (1996) J. Biol. Chem. 271:2543.

9. Liu, L. et al. (2005) J. Neurochem. 92:546.

10. Ponath, G. et al. (2007) J. Neuroimmunol. 184:214.

11. Bianchi, R. et al. (2007) J. Leukoc. Biol. 81:108.

• Long Name:

  S100 Calcium Binding Protein B

• Entrez Gene IDs:

  6285 (Human)

• Alternate Names:

  beta (neural); NEF; S100 beta; S100 calcium binding protein B; S100 calcium-binding protein B; S100 calcium-binding protein, beta (neural); S-100 calcium-binding protein, beta chain, 10protein S100-B; S-100 protein beta chain; S-100 protein subunit beta; S100; S100B; S100beta