Le '''S-100proteine proteinS100''' issono auna familyfamiglia ofdi low[[proteine]] moleculara weightbasso proteinpeso foundmolecolare inpresente vertebratesnei characterizedvertebrati, bycaratterizzate twoda [[calcium]]due bindingsiti sitesdi oflegame thedi [[helix-loop-helixcalcio]] ("della conformazione [[EF-hand]] type") conformationelica-loop-elica. ThereEsistono are at leastalmeno 21 differenttipo typesdi ofproteine S100 proteins.<ref name="pmid15336958">{{cite journal | author = Marenholz I, Heizmann CW, Fritz G | title = S100 proteins in mouse and man: from evolution to function and pathology (including an update of the nomenclature) | journal = Biochem. Biophys. Res. Commun. | volume = 322 | issue = 4 | pages = 1111–22 | year = 2004 | month = October | pmid = 15336958 | doi = 10.1016/j.bbrc.2004.07.096 | url = }}</ref>. TheIl namenome is''S100'' derivedderiva fromdalla thesolubilità factal that the protein is ''100''% '''S'''olubledi queste in [[ammoniumsolfato sulfated'ammonio]] at neutrala [[pH]]. neutro.
==Struttura==
La maggior parte delle S100 presentano una struttura omodimerica, cioè due [[polipeptidi]] identici legati tra loro da [[legame non coovalente|legami non coovalenti]]. Sebbene le S100 siano strutturalmente simili alle [[calmodulina|calmoduline]], differenziano da queste in quanto sono cellule-specifici, espressi in particolari cellule a diversi livelli a seconda dei fattori ambientali. Le calmoduline, invece, sono dei recettori Ca<sup>2+</sup> onnipresenti e universali per molte cellule.
==Funzione normale==
==Structure==
Most S100 proteins are homodimeric, consisting of two identical polypeptides held together by non-covalent bonds. Although S100 proteins are structurally similar to [[calmodulin]], they differ in that they are cell-specific, expressed in particular cells at different levels depending on environmental factors. To contrast, calmodulin is a ubiquitous and universal intracellular Ca<sup>2+</sup> receptor widely expressed in many cells.
