Figure 2.

Smc complex assembly. A cartoon of an Smc protein is shown on the left. Folding of the Smc molecule at the hinge generates the head domain and brings the Walker A site (important for ATP binding) and Walker B motif (important for ATPase activity) in close proximity to form a functional ATPase. Smc molecules can dimerize through their hinge motifs. The signature motif of each head domain can bind to the ATP associated with the other head domain of the dimer, generating a closed ring. The ring is stabilized by the binding of a kleisin molecule and other non-Smc proteins (not shown). In principle, oligomers of the Smc complex could occur through interactions of the hinge domains or coiled-coil domains. Alternatively, oligomers may form by the signature motif binding to a head domain of another dimer.