The gene encompasses 17.3 Kb of DNA; 3 exons (the first one contains the 5 untranslated region).

1135 b mRNA; 279 b coding sequence.

92 amino acids (including initial methionine that is generally processed in vivo);
10.5 kDa monomer (S100B can form homodimers and heterodimers with other proteins of the S100 family, described for S100A1).

S100B highest levels are found in brain. The protein is primarily found in astrocytes. Outside the central nervous system it can be found in chondrocytes and melanocytes.

Nuclear and cytoplasmic. It has both intracellular and extracellular roles.

The exact function of S100B is not fully understood. It inhibits microtubule assembly, has been involved in the regulation of cell cycle progression and differentiation and is able to induce neurite extension. This latest effect seems to be dependent on the concentration of S100B and occurs at nanomolar concentrations.
But micromolar levels of extracellular S100B stimulate apoptosis in vitro. Calcium binding induces a conformational change in S100B that allows the interaction with a variety of target proteins. These include p53 tumour suppressor, the microtubule-associated protein tau, the cytoskeletal protein tubulin (and its prokaryotic ancestor FtsZ), the scaffold protein IQGAP1, the intermediate filament protein glial fibrillary acidic protein (GFAP),the actin capping protein CapZ and the giant phosphoprotein AHNAK. Over-expression of S100B has been proposed to play a role in different neuro-pathologies.

S100B belongs to the S100 family of calcium binding proteins, a highly homologous family. These proteins contain two EF-hand calcium binding domains. The S100 genes are present exclusively in vertebrates.

Have not been reported.