Extended Human G-Protein Coupled Receptor Network: Cell-Type-Specific Analysis of G-Protein Coupled Receptor Signaling Pathways.

G-protein coupled receptors (GPCRs) mediate crucial physiological functions in humans, have been implicated in an array of diseases, and are therefore prime drug targets. GPCRs signal via a multitude of pathways, mainly through G-proteins and ß-arrestins, to regulate effectors responsible for cellular responses. The limited number of transducers results in different GPCRs exerting control on the same pathway, while the availability of signaling proteins in a cell defines the result of GPCR activation. The aim of this study was to construct the extended human GPCR network (hGPCRnet) and examine the effect that cell-type specificity has on GPCR signaling pathways. To achieve this, protein-protein interaction data between GPCRs, G-protein coupled receptor kinases (GRKs), Gα subunits, ß-arrestins, and effectors were combined with protein expression data in cell types. This resulted in the hGPCRnet, a very large interconnected network, and similar cell-type-specific networks in which, distinct GPCR signaling pathways were formed. Finally, a user friendly web application, hGPCRnet ( http://bioinformatics.biol.uoa.gr/hGPCRnet ), was created to allow for the visualization and exploration of these networks and of GPCR signaling pathways. This work, and the resulting application, can be useful in further studies of GPCR function and pharmacology.