The hetero-oligomeric complex of the S100A8/S100A9 protein is extremely protease resistant.

S100A8, S100A9 and S100A12 proteins are associated with inflammation and tissue remodelling, both processes known to be associated with high protease activity. Here, we report that homo-oligomeric forms of S100A8 and S100A9 are readily degraded by proteases, but that the preferred hetero-oligomeric S100A8/A9 complex displays a high resistance even against proteinase K degradation. S100A12 is not as protease resistant as the S100A8/A9 complex. Since specific functions have been assigned to the homo- and heterooligomeric forms of the S100A8 and A9 proteins, this finding may point to a post-translational level of regulation of the various functions of these proteins in inflammation and tissue remodelling.