The Caspase Recruitment Domain (CARD) from the innate immune receptor NOD1 was
crystallized with Ubiquitin (Ub). NOD1 CARD was present as a helix-swapped
homodimer similar to other structures of NOD1 CARD, and Ub monomers formed a
homodimer similar in conformation to Lys48-linked di-Ub. The interaction between
NOD1 CARD and Ub in the crystal was mediated by novel binding sites on each
molecule. Comparisons of these sites to previously identified interaction
surfaces on both molecules were made along with discussion of their potential
functional significance.
