While the presence of heptad repeats is fairly indicative of coiledcoil domains, it is difficult to determine from the sequence alone the oligomeric state, parallel versus antiparallel arrangement, and details of the coiled-coil packing and surface architecture 32 . These properties have direct bearing on the mechanism of assembly, the interpretation of mutations, and the interaction with other proteins or domains. For these reasons, we were interested in obtaining the high-resolution structure of the CLZ domains.