title: A direct comparison of protein interaction confidence assignment schemes.
abstract: BACKGROUND
  Recent technological advances have enabled high-throughput measurements of protein-protein interactions in the cell, producing large protein interaction networks for various species at an ever-growing pace. However, common technologies like yeast two-hybrid may experience high rates of false positive detection. To combat false positive discoveries, a number of different methods have been recently developed that associate confidence scores with protein interactions. Here, we perform a rigorous comparative analysis and performance assessment among these different methods.
  
  
  RESULTS
  We measure the extent to which each set of confidence scores correlates with similarity of the interacting proteins in terms of function, expression, pattern of sequence conservation, and homology to interacting proteins in other species. We also employ a new metric, the Signal-to-Noise Ratio of protein complexes embedded in each network, to assess the power of the different methods. Seven confidence assignment schemes, including those of Bader et al., Deane et al., Deng et al., Sharan et al., and Qi et al., are compared in this work.
  
  
  CONCLUSIONS
  Although the performance of each assignment scheme varies depending on the particular metric used for assessment, we observe that Deng et al. yields the best performance overall (in three out of four viable measures). Importantly, we also find that utilizing any of the probability assignment schemes is always more beneficial than assuming all observed interactions to be true or equally likely.
authors.affiliation: Department of Bioengineering, University of California, San Diego, CA 92093, USA. ssuthram@ucsd.edu
authors.forename: Silpa
authors.initials: S
authors.lastname: Suthram
authors.forename: Tomer
authors.initials: T
authors.lastname: Shlomi
authors.forename: Eytan
authors.initials: E
authors.lastname: Ruppin
authors.forename: Roded
authors.initials: R
authors.lastname: Sharan
authors.forename: Trey
authors.initials: T
authors.lastname: Ideker
mesh_terms: D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D030562:Databases, Protein; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D040901:Proteomics / Q000379:methods*; D015203:Reproducibility of Results; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid
chemical_list: D029742:Caenorhabditis elegans Proteins; D029721:Drosophila Proteins; D029701:Saccharomyces cerevisiae Proteins