A tale of two sites: How ubiquitination of a G protein-coupled receptor is coupled to its lysosomal trafficking from distinct receptor domains.

The β(2)-adrenergic receptor (β(2)AR) is a prototypical G(s)-coupled receptor belonging to the superfamily of seven transmembrane spanning heptahelical receptors (7TMRs or G protein-coupled receptors [GPCRs])-therapeutically the most diverse and accessible class of cell surface receptors. The classic pathway of β(2)AR signaling (Fig. 1) is triggered by activation of the heterotrimeric G protein G(s) by agonists (catecholamines-noradrenaline and adrenaline). This in turn activates adenylyl cyclase leading to the generation of second messenger signaling molecules (cyclic adenosine monophosphates, cAMP) which subsequently activate protein kinase A (PKA) as well as some ion channels, such as the class C type of L-type calcium channels, Ca(v)1.2.31 Here in we review how trafficking and signaling of the β(2)AR is regulated by the post-translational modification, ubiquitination.1.