title: Shuttling of G protein subunits between the plasma membrane and intracellular membranes.
abstract: Heterotrimeric G proteins (alphabetagamma) mediate the majority of signaling pathways in mammalian cells. It is long held that G protein function is localized to the plasma membrane. Here we examined the spatiotemporal dynamics of G protein localization using fluorescence recovery after photobleaching, fluorescence loss in photobleaching, and a photoswitchable fluorescent protein, Dronpa. Unexpectedly, G protein subunits shuttle rapidly (t1/2 < 1 min) between the plasma membrane and intracellular membranes. We show that consistent with such shuttling, G proteins constitutively reside in endomembranes. Furthermore, we show that shuttling is inhibited by 2-bromopalmitate. Thus, contrary to present thought, G proteins do not reside permanently on the plasma membrane but are constantly testing the cytoplasmic surfaces of the plasma membrane and endomembranes to maintain G protein pools in intracellular membranes to establish direct communication between receptors and endomembranes.
authors.affiliation: Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Chisari
authors.forename: Deepak Kumar
authors.initials: DK
authors.lastname: Saini
authors.forename: Vani
authors.initials: V
authors.lastname: Kalyanaraman
authors.forename: Narasimhan
authors.initials: N
authors.lastname: Gautam
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D007700:Kinetics; D010168:Palmitates / Q000494:pharmacology; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport
chemical_list: D010168:Palmitates; D021122:Protein Subunits; C022776:2-bromopalmitate; D019204:GTP-Binding Proteins