Laurel A. Grisanti et al. BTS 2018;3:550-562 GRKs Demonstrate Isoform-Specific Functions in the Regulation of Cardiac Signaling and Function AR = adrenergic receptor; ARKct = adrenergic receptor kinase carboxy-terminal peptide; AT1R = angiotensin II type 1A receptor; beta = beta subunit; G alpha q = G alpha q subunit; gamma = gamma subunit; GRK = G protein--coupled receptor kinase; GRK3ct = G protein–coupled receptor kinase 3 carboxy-terminal peptide; OE = over-expression. Laurel A. Grisanti et al. BTS 2018;3:550-562 2018 The Authors