ASC oligomerization is also regulated by ubiquitination and phosphorylation and two lysine residues that control the association with ZBTB16 have been identified as ubiquitination sites (at positions 21 and 22 or 22 and 23 in human or mouse ASC, respectively39,40). However, our experiments did not detect the interplay between ubiquitin and SUMO1. A potential connection to phosphorylation might be envisioned from our previous report that ZBTB16 regulates the NF-κB response, as the IκB kinase and Inhibitor of NF-κB kinase controls ASC6. However, no autoregulatory effect on the levels of these kinases was identified in Zbtb16-/- cells that might alter this phosphorylation activity22. Additionally, the residues identified (at positions; 46, 58, 60, 137 and 146 or 16, 144, 187 and 193 in human or mouse ASC, respectively39,40,47,48) differ from the residues we identify as controlling ASC SUMOylation and are not contiguous in the three-dimensional structure of ASC.
