D572–D574 Nucleic Acids Research, 2007, Vol. 35, Database issue doi:10.1093/nar/gkl950 Published online 29 November 2006 MINT: the Molecular INTeraction database Andrew Chatr-aryamontri, Arnaud Ceol, Luisa Montecchi Palazzi, Giuliano Nardelli, Maria Victoria Schneider, Luisa Castagnoli and Gianni Cesareni* Department of Biology, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy Received September 15, 2006; Revised October 18, 2006; Accepted October 20, 2006 ABSTRACT The Molecular INTeraction database (MINT, http:// mint.bio.uniroma2.it/mint/) aims at storing, in a structured format, information about molecular interactions (MIs) by extracting experimental details from work published in peer-reviewed journals. At present the MINT team focuses the curation work on physical interactions between proteins. Genetic or computationally inferred interactions are not included in the database. Over the past four years MINT has undergone extensive revision. The new version of MINT is based on a completely remodeled database structure, which offers more efficient data exploration and analysis, and is characterized by entries with a richer annotation. Over the past few years the number of curated physical interactions has soared to over 95 000. The whole dataset can be freely accessed online in both interactive and batch modes through web-based interfaces and an FTP server. MINT now includes, as an integrated addi- tion, HomoMINT, a database of interactions between human proteins inferred from experiments with ortholog proteins in model organisms (http://mint. bio.uniroma2.it/mint/). INTRODUCTION Cells are complex systems whose physiology is governed by an intricate network of molecular interactions (MIs) of which a relevant subset are protein–protein interactions (PPIs). Signal transduction pathways and transcriptional regulation are typical examples of such biological processes mediated by PPI. The MI database (MINT, http://mint.bio.uniroma2.it/mint/) was designed to collect experimentally veriﬁed PPIs in a binary or complex representation. Over the past four years, MINT has undergone a profound reorganization of both the data model and the database struc- ture, and has dramatically increased the number of stored interactions. DATABASE STRUCTURE In January 2006, MINT adopted the IntAct relational model. IntAct is an open source database designed for the storage, presentation and analysis of MIs (1) (schema available at http://intact.sourceforge.net/uml/intactCore.gif). The main advantages of adopting the IntAct model lie in its ability to represent protein complexes and other types of molecules as interaction participants, and in the ease with which new features and toolkits for data storage, representation and analysis can be added. In addition MINT, from now on, will be compatible with all the upgrades and tools developed by the IntAct consortium. MINT is based on the open source PostgreSQL database management system (http://www. postgresql.org). All the data can be accessed as Java objects through the IntAct API by using OJB (http://db.apache.org/ ojb/) as the object-relational mapping tool. The web applica- tion is based on the Struts framework (http://jakarta.apache. org/struts/) running on the Tomcat servlet container (http:// tomcat.apache.org/) and the Apache server (http://www. apache.org/). DATA GROWTH Since MINT was ﬁrst reported (2) the number of curated entries has grown signiﬁcantly. Given the new database struc- ture, binary and n-ary interactions can now be represented. The number of binary interactions has increased >20-fold (Figure 1). As of September 2006, more then 95 000 physical interactions involving 27 461 proteins from 325 organisms are stored in MINT (Figure 2). Although, 90% of the inter- actions stored in the database are the result of large scale, genome wide experiments, the value of MINT resides in the high number of curated articles, each of which reports a small number of interactions. This is reﬂected in the steady increase of curated articles that is mainly due to the curation of publications describing low-throughput experiments (Figure 1). The MINT curation team consists of two full- time and one part-time curators. This is not sufﬁcient to capture all the interaction information steadily reported in research articles. Thus, we have chosen to focus our efforts on consistently curating all the issues of FEBS Letters (since January 2005) and EMBO Journal and EMBO Reports *To whom correspondence should be addressed. Tel: +39 067 2594315; Fax: +39 062 023500; Email: Cesareni@uniroma2.it The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors 2006 The Author(s). 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