Promiscuity mapping of the S100 protein family using a high-throughput holdup assay.

S100 proteins are small, typically homodimeric, vertebrate-specific EF-hand proteins that establish Ca-dependent protein-protein interactions in the intra- and extracellular environment and are overexpressed in various pathologies. There are about 20 distinct human S100 proteins with numerous potential partner proteins. Here, we used a quantitative holdup assay to measure affinity profiles of most members of the S100 protein family against a library of chemically synthetized foldamers.