PT - JOURNAL ARTICLE AU - Michael P Hayes AU - Christopher R Bodle AU - David L. Roman TI - Evaluation of the Selectivity and Cysteine-Dependence of Inhibitors Across the Regulator of G Protein Signaling Family AID - 10.1124/mol.117.109843 DP - 2017 Jan 01 TA - Molecular Pharmacology PG - mol.117.109843 4099 - http://molpharm.aspetjournals.org/content/early/2017/10/19/mol.117.109843.short 4100 - http://molpharm.aspetjournals.org/content/early/2017/10/19/mol.117.109843.full AB - Since their discovery over 20 years ago, Regulators of G Protein Signaling (RGS) proteins have received considerable attention as potential drug targets due to their ability to modulate G α activity. Efforts to identify small molecules capable of inhibiting the protein-protein interaction between activated G α subunits and RGS proteins have yielded a substantial number of inhibitors, especially towards the well-studied RGS4. These efforts also identified that many of these small molecules inhibit the protein- protein interaction through covalent modification of Cysteine residues within the RGS domain that are located distal to the G α -binding interface. As some of these Cysteine residues are highly conserved within the RGS family, many of these inhibitors display activity towards multiple RGS family members. In this work we sought to determine the selectivity of these small molecule inhibitors against 12 RGS proteins, as well as against the Cysteine-null mutants for 10 of these proteins. Using both biochemical and cell- based methods to assess G α -RGS complex formation and G α enzymatic activity, we found that a number of previously identified RGS4 inhibitors were active against other RGS members, such as RGS14, with comparable or greater potency. Additionally, for every compound tested, activity was dependent upon the presence of Cysteine residues. This work defines the selectivity of commercially available RGS inhibitors and provides insight into the RGS family members for which drug discovery efforts may be most likely to succeed.