A dileucine motif in the C terminus of the β 2 -adrenergic receptor is involved in receptor internalization

• Published in: Proceedings of the National Academy of Sciences - PNAS 1997-11, Vol.94 (23), p.12285-12290
• Main Authors: Gabilondo, Ane M., Hegler, Jutta, Krasel, Cornelius, Boivin-Jahns, Valerie, Hein, Lutz, Lohse, Martin J.
• Format: Article
• Language: English
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.23.12285

The cytoplasmic C terminus of the β 2 -adrenergic receptor and many other G protein-coupled receptors contains a dileucine sequence that has been implicated in endosome/lysosome targeting of diverse proteins. In the present study, we provide evidence for an essential role of this motif in the agonist-induced internalization of the β 2 -adrenergic receptor. Mutation of Leu-339 and/or Leu-340 to Ala caused little changes in surface expression, ligand binding, G protein coupling, and signaling to adenylyl cyclase, when these receptors were transiently or stably expressed in CHO or HEK-293 cells. However, agonist-induced receptor internalization was markedly impaired in the L 339,340 A double mutant and reduced in the two single mutants. This impairment in receptor internalization was seen by using various approaches to determine internalization: binding of hydrophobic vs. hydrophilic ligands, loss of surface β 2 -adrenergic receptor immunoreactivity, and immunofluorescence microscopy. The selective effects of these mutations suggest that the C-terminal dileucine motif is involved in agonist-induced internalization of the β 2 -adrenergic receptor.