SMC-protein complexes, condensin, and cohesin, are conserved in eukaryotes. Their common structures are shown. An SMC2-SMC4 heterodimer functions as the core of condensin I and II. Condensin I contains the non-SMC subunits CAP-D2, CAP-H, and CAP-G; Condensin II contains CAP-D3, CAP-H2, and CAP-G2. An SMC1-SMC3 heterodimer functions as the core of the cohesin complex, which contains two non-SMC subunits, Rad21/Scc1 and SA proteins/Scc3. Redrawn with permission from Fig. 1 in (45).