Molecular architecture of SMC proteins and the yeast cohesin complex

Mol Cell. 2002 Apr;9(4):773-88. doi: 10.1016/s1097-2765(02)00515-4.


Sister chromatids are held together by the multisubunit cohesin complex, which contains two SMC (Smc1 and Smc3) and two non-SMC (Scc1 and Scc3) proteins. The crystal structure of a bacterial SMC "hinge" region along with EM studies and biochemical experiments on yeast Smc1 and Smc3 proteins show that SMC protamers fold up individually into rod-shaped molecules. A 45 nm long intramolecular coiled coil separates the hinge region from the ATPase-containing "head" domain. Smc1 and Smc3 bind to each other via heterotypic interactions between their hinges to form a V-shaped heterodimer. The two heads of the V-shaped dimer are connected by different ends of the cleavable Scc1 subunit. Cohesin therefore forms a large proteinaceous loop within which sister chromatids might be entrapped after DNA replication.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / chemistry
  • Bacterial Proteins / chemistry
  • Cell Cycle Proteins / chemistry*
  • Chondroitin Sulfate Proteoglycans*
  • Chromatids / metabolism
  • Chromosomal Proteins, Non-Histone / chemistry*
  • Cohesins
  • DNA Replication
  • Dimerization
  • Eukaryotic Cells / metabolism
  • Fungal Proteins / chemistry*
  • Macromolecular Substances
  • Models, Biological
  • Models, Molecular
  • Nuclear Proteins / chemistry*
  • Phosphoproteins
  • Prokaryotic Cells / metabolism
  • Protein Binding
  • Protein Conformation
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • Protein Subunits
  • Recombinant Fusion Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Structure-Activity Relationship
  • Thermotoga maritima / chemistry
  • X-Ray Diffraction


  • Bacterial Proteins
  • Cell Cycle Proteins
  • Chondroitin Sulfate Proteoglycans
  • Chromosomal Proteins, Non-Histone
  • Fungal Proteins
  • MCD1 protein, S cerevisiae
  • Macromolecular Substances
  • Nuclear Proteins
  • Phosphoproteins
  • Protein Subunits
  • Recombinant Fusion Proteins
  • SMC3 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • structural maintenance of chromosome protein 1
  • Adenosine Triphosphatases