TY - JOUR T1 - Analysis of the C-Terminal Tail of the Rat Thyrotropin-Releasing Hormone Receptor-1 in Interactions and Cointernalization with β-Arrestin 1-Green Fluorescent Protein JF - Molecular Pharmacology JO - Mol Pharmacol SP - 375 LP - 385 DO - 10.1124/mol.59.2.375 VL - 59 IS - 2 AU - D. Alex Groarke AU - Tomas Drmota AU - Daljit S. Bahia AU - Nicholas A. Evans AU - Shelagh Wilson AU - Graeme Milligan Y1 - 2001/02/01 UR - http://molpharm.aspetjournals.org/content/59/2/375.abstract N2 - Coexpression of the rat thyrotropin releasing hormone receptor-1 with β-arrestin 1-green fluorescent protein (GFP) in human embryonic kidney 293 cells results in agonist-dependent translocation of the arrestin to the plasma membrane followed by its cointernalization with the receptor. Truncations of the receptor C-terminal tail from 93 to 50 amino acids did not alter this. Truncations to fewer than 47 amino acids prevented such interactions and inhibited but did not fully eliminate agonist-induced internalization of the receptor. Deletion and site-directed mutants of the C-terminal tail indicated that separate elimination of a potential casein kinase II phosphorylation site or clathrin/clathrin adapter motifs was insufficient to prevent either internalization of the receptor or its cointernalization with β-arrestin 1-GFP. Alteration of sites of acylation reduced internalization and prevented interactions with β-arrestin 1-GFP. Combinations of these mutants resulted in lack of interaction with β-arrestin 1-GFP and a 10-fold reduction in internalization of the receptor. Despite this, the receptor construct that lacked the three protein sequence motifs was fully functional. These studies map sites that contribute the interactions of the thyrotropin releasing hormone receptor-1 C-terminal tail required for effective contacts with β-arrestin 1-GFP and indicate key roles for these interactions in agonist-induced internalization of the receptor. ER -