title: Evolutionary conservation of domain-domain interactions.
abstract: BACKGROUND
  Recently, there has been much interest in relating domain-domain interactions (DDIs) to protein-protein interactions (PPIs) and vice versa, in an attempt to understand the molecular basis of PPIs.
  
  
  RESULTS
  Here we map structurally derived DDIs onto the cellular PPI networks of different organisms and demonstrate that there is a catalog of domain pairs that is used to mediate various interactions in the cell. We show that these DDIs occur frequently in protein complexes and that homotypic interactions (of a domain with itself) are abundant. A comparison of the repertoires of DDIs in the networks of Escherichia coli, Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and Homo sapiens shows that many DDIs are evolutionarily conserved.
  
  
  CONCLUSIONS
  Our results indicate that different organisms use the same 'building blocks' for PPIs, suggesting that the functionality of many domain pairs in mediating protein interactions is maintained in evolution.
authors.affiliation: Department of Molecular Genetics and Biotechnology, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
authors.forename: Zohar
authors.initials: Z
authors.lastname: Itzhaki
authors.forename: Eyal
authors.initials: E
authors.lastname: Akiva
authors.forename: Yael
authors.initials: Y
authors.lastname: Altuvia
authors.forename: Hanah
authors.initials: H
authors.lastname: Margalit
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017173:Caenorhabditis elegans / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism
chemical_list: D011506:Proteins