Components of the G <sub>s</sub> signaling cascade exhibit distinct changes in mobility and membrane domain localization upon β <sub>2</sub> ‐adrenergic receptor activation
Alexey Bondar, Wonjo Jang, Ekaterina Sviridova, Nevin A. Lambert
Abstract
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 G s signaling cascade members expressed at very low levels exhibit altered mobility and localize in clathrin‐coated structures (CCSs) or caveolae upon activation by β 2 ‐adrenergic receptors (β 2 AR). Activated β 2 AR showed decreased mobility and sustained accumulation in CCSs but not in caveolae. Arrestin 3 translocated to the plasma membrane after β 2 AR activation and showed very low mobility and pronounced accumulation in CCSs. In contrast, Gα s and Gγ 2 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 β 2 AR stimulation, no redistribution to CCSs, and weak activation‐independent accumulation in caveolae. Our findings show an overall decrease in the mobility of most activated G s signaling cascade members and confirm that β 2 AR and arrestin 3 accumulate in CCSs, while Gα s , Gγ 2 and AC5 can transiently enter CCSs and caveolae but do not accumulate in and are not excluded from these domains.