FIGURE 2.

The structure of the dual zinc cluster in XMcm10-CTD. A, backbone superposition of the twenty lowest energy NMR structures of XMcm10^755–842. Regions in red correspond to unrestrained terminal regions, which have been omitted from subsequent figures. B, XMcm10^755–842 depicted as a ribbon and superimposed onto a transparent gray molecular surface. Individual CCCH and CCCC zinc motifs are colored blue and green, respectively, and Zn²⁺ ions are depicted as red spheres. C, sequence alignment of the C-terminal region of Mcm10 proteins from X. laevis (Xl), Homo sapiens (Hs), Mus Musculus (Mm), Caenorhabditis elegans (Ce), and Drosophila melanogaster (Dm). The secondary structure is shown schematically above the sequence, and Zn²⁺-coordinating residues are highlighted with triangles below.