Components of the Gs signaling cascade exhibit distinct changes in mobility and membrane domain localization upon β2-adrenergic receptor activation

Abstract

The G protein signaling cascade is a key player in cell signaling. Cascade activation leads to a redistribution of its members in various cellular compartments. These changes are likely related to the “second wave” of signaling from endosomes. Here, we set out to determine whether Gs signaling cascade members expressed at very low levels exhibit altered mobility and localize in clathrin-coated structures (CCSs) or caveolae upon activation by β2-adrenergic receptors (β2AR). Activated β2AR showed decreased mobility and sustained accumulation in CCSs but not in caveolae. Arrestin 3 translocated to the plasma membrane after β2AR activation and showed very low mobility and pronounced accumulation in CCSs. In contrast, Gαs and Gγ2 exhibited a modest reduction in mobility but no detectable accumulation in or exclusion from CCSs or caveolae. The effector adenylyl cyclase 5 (AC5) showed a slight mobility increase upon β2AR stimulation, no redistribution to CCSs, and weak activation-independent accumulation in caveolae. Our findings show an overall decrease in the mobility of most activated Gs signaling cascade members and confirm that β2AR and arrestin 3 accumulate in CCSs, while Gαs, Gγ2 and AC5 can transiently enter CCSs and caveolae but do not accumulate in and are not excluded from these domains.