A handcuff model for the cohesin complex

J Cell Biol. 2008 Dec 15;183(6):1019-31. doi: 10.1083/jcb.200801157.


The cohesin complex is responsible for the accurate separation of sister chromatids into two daughter cells. Several models for the cohesin complex have been proposed, but the one-ring embrace model currently predominates the field. However, the static configuration of the embrace model is not flexible enough for cohesins to perform their functions during DNA replication, transcription, and DNA repair. We used coimmunoprecipitation, a protein fragment complement assay, and a yeast two-hybrid assay to analyze the protein-protein interactions among cohesin subunits. The results show that three of the four human cohesin core subunits (Smc1, Smc3, and Rad21) interact with themselves in an Scc3 (SA1/SA2)-dependent manner. These data support a two-ring handcuff model for the cohesin complex, which is flexible enough to establish and maintain sister chromatid cohesion as well as ensure the fidelity of chromosome segregation in higher eukaryotes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Cell Cycle Proteins / metabolism*
  • Chromatids / metabolism
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Cohesins
  • DNA-Binding Proteins
  • Genetic Complementation Test
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Luminescent Proteins / metabolism
  • Models, Biological*
  • Multiprotein Complexes / metabolism*
  • Nuclear Proteins / metabolism
  • Phosphoproteins / metabolism
  • Protein Binding
  • Protein Subunits / metabolism
  • Two-Hybrid System Techniques


  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Luminescent Proteins
  • Multiprotein Complexes
  • Nuclear Proteins
  • Phosphoproteins
  • Protein Subunits
  • RAD21 protein, human