TY - JOUR T1 - Differentiation of Opioid Drug Effects by Hierarchical Multi-site Phosphorylation JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.112.082875 SP - mol.112.082875 AU - Sascha Just AU - Susann Illing AU - Michelle Trester-Zedlitz AU - Elaine K Lau AU - Sarah J Kototowski AU - Elke Miess AU - Anika Mann AU - Christian Doll AU - Jonathan C Trinidad AU - Alma L Burlingame AU - Mark von Zastrow AU - Stefan Schulz Y1 - 2012/12/13 UR - http://molpharm.aspetjournals.org/content/early/2012/12/13/mol.112.082875.abstract N2 - Differences in the ability of opioid drugs to promote regulated endocytosis of μ-opioid receptors are related to their tendency to produce drug tolerance and dependence. Here we show that drug-specific differences in receptor internalization are determined by a conserved, 10 residue sequence in the receptor's carboxyl-terminal cytoplasmic tail. Diverse opioids induce receptor phosphorylation at S375, present in the middle of this sequence, but opioids differ markedly in their ability to drive higher-order phosphorylation on flanking residues (T370, T376 and T379). Multi-phosphorylation is required for the endocytosis-promoting activity of this sequence and occurs both sequentially and hierarchically, with S375 representing the initiating site. Higher-order phosphorylation involving T370, T376 and T379 specifically requires GRK2/3 isoforms, and the same sequence controls opioid receptor internalization in neurons. These results reveal a biochemical mechanism differentiating the endocytic activity of opioid drugs. ER -