iPHACE is an integrative web-based tool to navigate in the pharmacological space defined by small molecule drugs present in the IUPHAR-DB database, with additional interactions from the PDSP database. The current release (1.0) contains 4,089 interactions between 739 drugs and 181 targets, covering 147 G protein-coupled receptors (GPCR) and 34 ligand-gated ion channels (IC). Of those, a total of 2,122 interactions between 739 drugs and 140 targets come from IUPHAR-DB, supplemented with 3,009 interactions between 330 of those drugs and 121 targets from PDSP. Since only the portion of PDSP that contributes with interactions to drugs present in IUPHAR-DB is considered at present, we will refer to PDSP as PDSP*. Note thus that targets belonging to protein families other than GPCR and IC (such as enzymes or nuclear receptors) are not represented in the current release (1.0). For the sake of clarity, the target coverage in iPHACE from each individual source (IUPHAR-DB and PDSP*) and the database ensemble (All DBs) is represented in the figures below.
Data completeness is a major issue for all pharmacological resources as drugs are never tested systematically against all targets but solely to the ones of relevance to the project at work (Nat Biotechnol 2008; 26: 983; Mol BioSyst 2009; 5: 1051). The figures below illustrates the current data completeness in iPHACE from each individual source (IUPHAR-DB and PDSP*) and the database ensemble (All DBs). Interestingly, while 40% and 13% of the drugs in IUPHAR-DB and PDSP*, respectively, contain one target interaction only, 10% and 42% of the drugs in IUPHAR-DB and PDSP*, respectively, contain interaction data for more than five targets.