The EF-hand calcium-binding protein S100B has been
shown to interact in vitro in a calcium-sensitive manner
with many substrates. These potential S100B target proteins
have been screened for the preservation of a previously
identified consensus sequence across species. The results
were compared to known structural and in vitro properties
of the proteins to rationalize choices for potential binding
partners. Our approach uncovered four oligomeric proteins
tubulin (α and β), glial fibrillary acidic protein
(GFAP), desmin, and vimentin that have conserved regions
matching the consensus sequence. 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 sequence matches correspond to regions of α and
β tubulin found at the αβ tubulin interface.
In both cases, these consensus sequence matches provide
a logical explanation for in vitro observations that S100B
is able to inhibit oligomerization of these proteins.