A logical sequence search for S100B target proteins

The EF-hand calcium-binding protein S100B has been shown to interact in vit ro in a calcium-sensitive manner with many substrates, These potential S100 B target proteins have been screened for the preservation of a previously i dentified consensus sequence across species. The results were compared to k nown structural and in vitro properties of the proteins to rationalize choi ces fur potential binding partners. Our approach uncovered four oligomeric proteins tubulin (alpha and beta), glial fibrillary acidic protein (GFAP), desmin, and vimentin that have conserved regions matching the consensus seq uence. In the type III intermediate filament proteins (GFAP, vimentin, and desmin), this region corresponds to a portion of a coiled-coil (helix 2A), the structural element responsible for their assembly. In tubulin, the sequ ence matches correspond to regions of alpha and beta tubulin found at the a lpha beta tubulin interface. In both cases, these consensus sequence matche s provide a logical explanation for in vitro observations that S100B is abl e to inhibit oligomerization of these proteins.