“…In some cases the same receptor apparently uses different internalization pathways under different circumstances Lee et al, 2000). Arrestin was found to be necessary for desensitization but not for the internalization of some receptors , and even the active receptor conformation recognized by G proteins and GRKs/arrestins was reported to be different in some cases Vilardaga et al, 2001;Whistler et al, 2002b;Kohout et al, 2004;Hunton et al, 2005;Ponimaskin et al, 2005). Thus, one is left wondering whether these data can be reconciled with the "central dogma" of GRK and arrestin function in GPCR regulation.…”