title: modPDZpep: a web resource for structure based analysis of human PDZ-mediated interaction networks.
abstract: BACKGROUND
  PDZ domains recognize short sequence stretches usually present in C-terminal of their interaction partners. Because of the involvement of PDZ domains in many important biological processes, several attempts have been made for developing bioinformatics tools for genome-wide identification of PDZ interaction networks. Currently available tools for prediction of interaction partners of PDZ domains utilize machine learning approach. Since, they have been trained using experimental substrate specificity data for specific PDZ families, their applicability is limited to PDZ families closely related to the training set. These tools also do not allow analysis of PDZ-peptide interaction interfaces.
  
  
  RESULTS
  We have used a structure based approach to develop modPDZpep, a program to predict the interaction partners of human PDZ domains and analyze structural details of PDZ interaction interfaces. modPDZpep predicts interaction partners by using structural models of PDZ-peptide complexes and evaluating binding energy scores using residue based statistical pair potentials. Since, it does not require training using experimental data on peptide binding affinity, it can predict substrates for diverse PDZ families. Because of the use of simple scoring function for binding energy, it is also fast enough for genome scale structure based analysis of PDZ interaction networks. Benchmarking using artificial as well as real negative datasets indicates good predictive power with ROC-AUC values in the range of 0.7 to 0.9 for a large number of human PDZ domains. Another novel feature of modPDZpep is its ability to map novel PDZ mediated interactions in human protein-protein interaction networks, either by utilizing available experimental phage display data or by structure based predictions.
  
  
  CONCLUSIONS
  In summary, we have developed modPDZpep, a web-server for structure based analysis of human PDZ domains. It is freely available at http://www.nii.ac.in/modPDZpep.html or http://202.54.226.235/modPDZpep.html .
  
  
  METHODS
  This article was reviewed by Michael Gromiha and Zoltán Gáspári.
authors.affiliation: Bioinformatics Center, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Neetu
authors.initials: N
authors.lastname: Sain
authors.affiliation: Bioinformatics Center, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India. deb@nii.res.in.
authors.forename: Debasisa
authors.initials: D
authors.lastname: Mohanty
keywords: C-terminal peptides; PDZ domain; Protein-protein interaction networks; Structure based approach