title: An evolutionary and structural characterization of mammalian protein complex organization.
abstract: BACKGROUND
  We have recently released a comprehensive, manually curated database of mammalian protein complexes called CORUM. Combining CORUM with other resources, we assembled a dataset of over 2700 mammalian complexes. The availability of a rich information resource allows us to search for organizational properties concerning these complexes.
  
  
  RESULTS
  As the complexity of a protein complex in terms of the number of unique subunits increases, we observed that the number of such complexes and the mean non-synonymous to synonymous substitution ratio of associated genes tend to decrease. Similarly, as the number of different complexes a given protein participates in increases, the number of such proteins and the substitution ratio of the associated gene also tends to decrease. These observations provide evidence relating natural selection and the organization of mammalian complexes. We also observed greater homogeneity in terms of predicted protein isoelectric points, secondary structure and substitution ratio in annotated versus randomly generated complexes. A large proportion of the protein content and interactions in the complexes could be predicted from known binary protein-protein and domain-domain interactions. In particular, we found that large proteins interact preferentially with much smaller proteins.
  
  
  CONCLUSIONS
  We observed similar trends in yeast and other data. Our results support the existence of conserved relations associated with the mammalian protein complexes.
authors.affiliation: Helmholtz Center Munich-German Research Center for Environmental Health (GmbH), Institute of Bioinformatics and Systems Biology, Ingolstädter Landstrasse 1, Neuherberg, Germany. philip.wong@helmholtz-muenchen.de
authors.forename: Philip
authors.initials: P
authors.lastname: Wong
authors.forename: Sonja
authors.initials: S
authors.lastname: Althammer
authors.forename: Andrea
authors.initials: A
authors.lastname: Hildebrand
authors.forename: Andreas
authors.initials: A
authors.lastname: Kirschner
authors.forename: Philipp
authors.initials: P
authors.lastname: Pagel
authors.forename: Bernd
authors.initials: B
authors.lastname: Geissler
authors.forename: Pawel
authors.initials: P
authors.lastname: Smialowski
authors.forename: Florian
authors.initials: F
authors.lastname: Blöchl
authors.forename: Matthias
authors.initials: M
authors.lastname: Oesterheld
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schmidt
authors.forename: Normann
authors.initials: N
authors.lastname: Strack
authors.forename: Fabian J
authors.initials: FJ
authors.lastname: Theis
authors.forename: Andreas
authors.initials: A
authors.lastname: Ruepp
authors.forename: Dmitrij
authors.initials: D
authors.lastname: Frishman
mesh_terms: D000818:Animals; D019295:Computational Biology / Q000379:methods; D030562:Databases, Protein; D019143:Evolution, Molecular; D016014:Linear Models; D008322:Mammals; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000032:analysis*; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D040901:Proteomics / Q000379:methods; D020539:Sequence Analysis, Protein
chemical_list: D046912:Multiprotein Complexes