UML diagram of concepts related to oligomerization-induced phenotype changes. The GPCR oligomerization ontology focuses on changes in the phenotype that occur when GPCR protomers oligomerize. There are three types of phenotypic change that are described by the ontology: changes in internalization, changes in signaling, and differences in the ligand binding of the oligomer as compared to any of the constituent protomers. The effect that ligand(s) binding to one or more of the protomers in an oligomer may have on binding of ligands to other protomers, or on the change in signaling, is described by the CrossTalk concept. The Internalization concept is used to describe changes that different ligands have on the trafficking of the Oligomer to the cell membrane. Any information that is available about the mechanism of activation of the Oligomer is stored in the MechanismOfActivation concept. The PhysiologicalRelevance concept stores information about the Oligomer in vivo.