scholarly journals Inhibition of G protein-coupled receptor trafficking in neuroblastoma cells by MAP 4 decoration of microtubules

2002 ◽  
Vol 283 (6) ◽  
pp. H2379-H2388 ◽  
Author(s):  
Guangmao Cheng ◽  
Yoshihiro Iijima ◽  
Yuji Ishibashi ◽  
Dhandapani Kuppuswamy ◽  
George Cooper
Keyword(s):  
G Protein ◽  
Muscarinic Receptor ◽  
Receptor Binding ◽  
Neuroblastoma Cells ◽  
Pressure Overload ◽  
G Protein Coupled Receptors ◽  
Structural Protein ◽  
Microtubule Network ◽  
Intact Cells ◽  
G Protein Coupled

One mechanism for the reappearance of G protein-coupled receptors after agonist activation is microtubule-based transport. In pressure-overload cardiac hypertrophy, there is downregulation of G protein-coupled receptors and the appearance of a densified microtubule network extensively decorated by a microtubule-associated protein, MAP 4. Our hypothesis is that overdecoration of a dense microtubule network with this structural protein, as in hypertrophied myocardium, would impede receptor recovery. We tested this hypothesis by studying muscarinic acetylcholine receptor (mAChR) internalization and recovery after agonist stimulation in neuroblastoma cells. Exposure of cells to carbachol, a muscarinic receptor agonist, decreased membrane receptor binding activity. After carbachol withdrawal, receptor binding recovered toward the initial value. When microtubules were depolymerized before carbachol withdrawal, mAChR recovery was only 44% of that in intact cells. Cells were then infected with an adenovirus containing MAP 4 cDNA. MAP 4 protein decorated the microtubules extensively, and receptor recovery upon carbachol withdrawal was reduced to 54% of control. Thus muscarinic receptor recovery after agonist exposure is microtubule dependent, and MAP 4 decoration of microtubules inhibits receptor recovery.

Oligomerisation of G-protein-coupled receptors

2001 ◽  
Vol 114 (7) ◽  
pp. 1265-1271 ◽  
Author(s):  
G. Milligan
Keyword(s):  
Energy Transfer ◽  
Cell Surface ◽  
G Protein ◽  
Living Cells ◽  
G Protein Coupled Receptors ◽  
Intact Cells ◽  
Effective Delivery ◽  
Multiple Copies ◽  
Agonist Ligands ◽  
G Protein Coupled

A range of approaches have recently provided evidence that G-protein-coupled receptors can exist as oligomeric complexes. Both homo-oligomers, comprising multiple copies of the same gene product, and hetero-oligomers containing more than one receptor have been detected. In several, but not all, examples, the extent of oligomerisation is regulated by the presence of agonist ligands, and emerging evidence indicates that receptor hetero-oligomers can display distinct pharmacological characteristics. A chaperonin-like role for receptor oligomerisation in effective delivery of newly synthesised receptors to the cell surface is a developing concept, and recent studies have employed a series of energy-transfer techniques to explore the presence and regulation of receptor oligomerisation in living cells. However, the majority of studies have relied largely on co-immunoprecipitation techniques, and there is still little direct information on the fraction of receptors existing as oligomers in intact cells.

scholarly journals Structural Basis of Arrestin Selectivity for Active Phosphorylated G Protein-Coupled Receptors

2021 ◽  
Vol 22 (22) ◽  
pp. 12481
Author(s):  
Preethi C. Karnam ◽  
Sergey A. Vishnivetskiy ◽  
Vsevolod V. Gurevich
Keyword(s):  
G Protein ◽  
Receptor Binding ◽  
G Protein Coupled Receptors ◽  
Structural Basis ◽  
Preferential Binding ◽  
High Affinity Receptor ◽  
Functional Forms ◽  
Affinity Receptor ◽  
G Protein Coupled ◽  
Receptor Conformation

Arrestins are a small family of proteins that bind G protein-coupled receptors (GPCRs). Arrestin binds to active phosphorylated GPCRs with higher affinity than to all other functional forms of the receptor, including inactive phosphorylated and active unphosphorylated. The selectivity of arrestins suggests that they must have two sensors, which detect receptor-attached phosphates and the active receptor conformation independently. Simultaneous engagement of both sensors enables arrestin transition into a high-affinity receptor-binding state. This transition involves a global conformational rearrangement that brings additional elements of the arrestin molecule, including the middle loop, in contact with a GPCR, thereby stabilizing the complex. Here, we review structural and mutagenesis data that identify these two sensors and additional receptor-binding elements within the arrestin molecule. While most data were obtained with the arrestin-1-rhodopsin pair, the evidence suggests that all arrestins use similar mechanisms to achieve preferential binding to active phosphorylated GPCRs.

scholarly journals Few Residues within an Extensive Binding Interface Drive Receptor Interaction and Determine the Specificity of Arrestin Proteins

2011 ◽  
Vol 286 (27) ◽  
pp. 24288-24299 ◽  
Author(s):  
Sergey A. Vishnivetskiy ◽  
Luis E. Gimenez ◽  
Derek J. Francis ◽  
Susan M. Hanson ◽  
Wayne L. Hubbell ◽  
...  
Keyword(s):  
G Protein ◽  
Receptor Binding ◽  
Receptor Interaction ◽  
Receptor Subtypes ◽  
Phosphate Binding ◽  
D2 Dopamine Receptors ◽  
Intact Cells ◽  
Binding Interface ◽  
G Protein Coupled

Arrestins bind active phosphorylated forms of G protein-coupled receptors, terminating G protein activation, orchestrating receptor trafficking, and redirecting signaling to alternative pathways. Visual arrestin-1 preferentially binds rhodopsin, whereas the two non-visual arrestins interact with hundreds of G protein-coupled receptor subtypes. Here we show that an extensive surface on the concave side of both arrestin-2 domains is involved in receptor binding. We also identified a small number of residues on the receptor binding surface of the N- and C-domains that largely determine the receptor specificity of arrestins. We show that alanine substitution of these residues blocks the binding of arrestin-1 to rhodopsin in vitro and of arrestin-2 and -3 to β2-adrenergic, M2 muscarinic cholinergic, and D2 dopamine receptors in intact cells, suggesting that these elements critically contribute to the energy of the interaction. Thus, in contrast to arrestin-1, where direct phosphate binding is crucial, the interaction of non-visual arrestins with their cognate receptors depends to a lesser extent on phosphate binding and more on the binding to non-phosphorylated receptor elements.

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