CCR5 is a chemokine receptor belonging to the superfamily of GPCRs, which are involved in various physiological/pathological processes. Upon agonist activation GPCRs trigger the activation of G proteins, followed by receptor intracellular phosphorylation and recruitment of arrestins. Arrestins are cytosolic proteins responsible for blocking G protein-mediated signalling, orchestrating receptor desensitization/post-endocytic intracellular trafficking and activating G protein-independent signalling. The capacity of certain ligands to preferentially elicit the G protein over the arrestin pathway, or vice versa, is designated ligand bias and is of great importance for drug discovery. A better understanding of (i) how arrestin recruitment to GPCRs is regulated, (ii) the potential role of phosphorylation patterns in that process as well as (iii) the phenomenon of ligand bias is required in the GPCR field, using new receptor models and well-characterized ligands. Here a panel of CCR5 chemokine analogs discovered and optimized by our group was used to investigate these phenomena.