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. 2016 Aug 3;5:F1000 Faculty Rev-1909. [Version 1] doi: 10.12688/f1000research.8881.1

Figure 1. The cohesin complex.

Figure 1.

The four-subunit complex contains two SMC proteins, each of which forms long antiparallel coiled-coils. The SMC proteins interact in two places: where they fold back on themselves (hinge domains) and at head domains formed by interaction of their N and C termini. The interactions of the Smc1 and Smc3 head domains together form two intermolecular ATPases. ATP is indicated by yellow diamonds. Note that the Smc1 and 3 subunits, when interacting at both the hinge and the ATPase domains, would form a structure with an internal pore. The Mcd1 subunit (blue) interacts with both SMC head domains. Because the ATPase domains interact, a second pore may exist between Mcd1 and the Smc proteins. Separation of the Smc ATPase domains by ATP hydrolysis would create a single pore surrounded by Mcd1, Smc3, and Smc1. The Scc3 subunit, shown in grey, is not thought to form part of the ring.