This is a family of prokaryotic proteins that form one of the subunits, ScpB, of the segregation and condensation complex, condensin, that plays a key role in the maintenance of the chromosome. In prokaryotes the complex consists of three proteins, SMC, ScpA (kleisin) and ScpB. ScpB dimerises and binds to ScpA. As originally predicted, ScpB is structurally a winged-helix at both its N- and C-terminal halves. IN Bacillus subtilis,one Smc dimer is bridged by a single ScpAB to generate asymmetric tripartite rings analogous to eukaryotic SMC complex ring-shaped assemblies [1,2].

1: An asymmetric SMC-kleisin bridge in prokaryotic condensin. Burmann F, Shin HC, Basquin J, Soh YM, Gimenez-Oya V, Kim YG, Oh BH, Gruber S; Nat Struct Mol Biol. 2013;20:371-379. PMID:23353789

2: Molecular basis of SMC ATPase activation: role of internal structural changes of the regulatory subcomplex ScpAB. Kamada K, Miyata M, Hirano T; Structure. 2013;21:581-594. PMID:23541893