title: Modulation of quaternary structure of S100 proteins by calcium ions.
abstract: It is well established that calcium binding leads to conformational changes in S100 proteins. These conformational changes are thought to activate the protein and render a protein conformation that is capable of binding other proteins. The basic quaternary structural motif of S100 proteins is a homodimer, however there is little information if higher order non-covalent oligomers are also formed and whether these oligomers are of functional relevance. To this end we performed equilibrium analytical ultracentrifugation experiments for 16 S100 proteins (S100A1, S100A2, S100A3, S100A4, S100A5, S100A6, S100A7, S100A8, S100A9, S100A10, S100A11, S100A12, S100A13, S100B, S100P, and S100Z) under reducing conditions in the absence and presence of calcium ions. We show that the addition of calcium promotes the formation of tetrameric structures which could be further enhanced under in vivo conditions where there is an additional effect of molecular crowding.
authors.affiliation: Center for Biotechnology and Interdisciplinary Studies and Department of Biology, Rensselaer Polytechnic Institute, Troy, NY 12065, USA.
authors.forename: Werner W
authors.initials: WW
authors.lastname: Streicher
authors.forename: Maria M
authors.initials: MM
authors.lastname: Lopez
authors.forename: George I
authors.initials: GI
authors.lastname: Makhatadze
mesh_terms: D019540:Area Under Curve; D002118:Calcium / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D055503:Protein Multimerization / Q000187:drug effects; D020836:Protein Structure, Quaternary / Q000187:drug effects*; D009418:S100 Proteins / Q000737:chemistry* / Q000378:metabolism; D014461:Ultracentrifugation
chemical_list: D009418:S100 Proteins; D002118:Calcium