SMCkleisin
SMCkleisin refers to the kleisin family of proteins that form the central connecting subunit of Structural Maintenance of Chromosomes (SMC) complexes. Kleisins bridge the ATPase head domains of paired SMC proteins to close a tripartite ring that entraps DNA, a configuration essential for chromosome cohesion, condensation, and DNA repair. Different SMC complexes contain distinct kleisin paralogs (for example, cohesin and condensin kleisins), but they share a conserved role in linking SMC heterodimers and recruiting accessory factors.
Structurally, kleisins have an extended central region that binds regulatory subunits and flexible N- and C-terminal
Kleisins are conserved across bacteria, archaea, and eukaryotes, though sequence and regulatory complexity increase in higher