Determination of the Affinities between Heterotrimeric G Protein Subunits and Their Phospholipase C-β Effectors†

Biochemistry ◽  
1999 ◽  
Vol 38 (5) ◽  
pp. 1488-1496 ◽  
Author(s):  
Loren W. Runnels ◽  
Suzanne F. Scarlata
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
Heterotrimeric G Protein ◽  
Protein Subunits

scholarly journals Activation of Phospholipase C-ε by Heterotrimeric G Protein βγ-Subunits

2001 ◽  
Vol 276 (51) ◽  
pp. 48257-48261 ◽  
Author(s):  
Michele R. Wing ◽  
Dayle Houston ◽  
Grant G. Kelley ◽  
Channing J. Der ◽  
David P. Siderovski ◽  
...  
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
Heterotrimeric G Protein

Dexamethasone increases G alpha q-11 expression and hormone-stimulated phospholipase C activity in UMR-106-01 cells.

1997 ◽  
Vol 273 (3) ◽  
pp. E528 ◽  
Author(s):  
J Mitchell ◽  
A Bansal
Keyword(s):  
Adenylyl Cyclase ◽  
Phospholipase C ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Beta Subunits ◽  
Adenylyl Cyclase Activity ◽  
Protein Subunits ◽  
G Alpha Q ◽  
Umr 106 ◽  
G Protein Coupled

Glucocorticoids regulate responsiveness of many cells to hormones that bind to G protein-coupled receptors. We examined the effect of glucocorticoids on parathyroid hormone (PTH) activation of two G protein-activated signal transduction pathways, phospholipase C (PLC) and adenylyl cyclase, in osteosarcoma UMR-106-01 cells. Dexamethasone (100 nM) increased PTH-stimulated and NaF-stimulated PLC activity by > 100% over 4 days (223 +/- 8 and 293 +/- 8.2% of control after 4 days for PTH and NaF-stimulated activity, respectively). The increase in PTH-stimulated adenylyl cyclase response in the same cells was more modest (162 +/- 5.4 and 171 +/- 6.8% of control after 4 days for PTH and NaF-stimulated activity, respectively). PTH activation of PLC was blocked by antiserums to G alpha q-11 and activation of adenylyl cyclase by G alpha s antiserums. Quantification of these G protein subunits in control and dexamethasone-treated cells showed a 78% increase in G alpha q-11 (from 18.1 +/- 1.2 to 32.2 +/- 1.5 pmol/mg), whereas G alpha s was increased only 34% (from 6.2 +/- 0.5 to 8.2 +/- 0.3 pmol/mg) and G beta-subunits were increased 40% (from 54 +/- 2.3 to 75.2 +/- 3.8 pmol/mg). These results suggest that glucocorticoids are more potent regulators of PLC activity than adenylyl cyclase activity in UMR cells, and this is mediated, at least in part, by differential increases in G alpha q-11 proteins.

scholarly journals Role of Dynamic Interactions in Effective Signal Transfer for Gβ Stimulation of Phospholipase C-β2

2002 ◽  
Vol 277 (51) ◽  
pp. 49707-49715 ◽  
Author(s):  
Elizabeth Buck ◽  
Peter Schatz ◽  
Suzanne Scarlata ◽  
Ravi Iyengar
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
Binding Affinity ◽  
Protein Interactions ◽  
Signal Transfer ◽  
Dynamic Interactions ◽  
Protein Subunits ◽  
Functional Studies ◽  
Effective Signal ◽  
Stimulation Of

Heterotrimeric G protein subunits regulate their effectors by protein-protein interactions. The regions involved in these direct interactions have either signal transfer or general binding functions (Buck, E., Li, J., Chen, Y., Weng, G., Scarlata, S., and Iyengar, R. (1999) Science 283, 1332–1335). Although key determinants of signal transfer regions for G protein subunits have been identified, the mechanisms of signal transfer are not fully understood. We have used a combinatorial peptide approach to analyze one Gβ region, Gβ86–105, involved in signal transfer to the effector phospholipase C (PLC)-β2 to gain a more mechanistic understanding of Gβ/PLC-β2 signaling. Binding and functional studies with the combinatorial peptides on interaction with and stimulation/inhibition of phospholipase Cβ2 indicate that binding affinity can be resolved from EC50for functional effects, such that peptides that have wild type binding affinities have 15- to 20-fold lower EC50values. Although more potent, these peptides display a much lower extent of maximal stimulation. These peptides synergize with Gβγ or peptides encoding the second Gβ42–54 signal transfer region in maximally stimulating phospholipase C-β2. Other combinatorial peptides from the Gβ86–105 region that bind to PLC-β2 by themselves submaximally stimulate and extensively inhibit Gβγ stimulation of PLC-β2. The intrinsic stimulation function can be attributed to Arg-96 and Ser-97, the synergy function to Trp-99, and the binding affinity to Thr-87, Val-90, Pro-94, Arg-96, Ser-97, and Val-100. These results indicate that, even within signal transfer regions, residues involved in binding can be resolved from those involved in signal transfer and that signal transfer is likely to be achieved through dynamic rather than steady-state interactions.

Subunits βγ of heterotrimeric G protein activate β2 isoform of phospholipase C

Nature ◽  
1992 ◽  
Vol 360 (6405) ◽  
pp. 686-689 ◽  
Author(s):  
Arieh Katz ◽  
Dianqing Wu ◽  
Melvin I. Simon
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
Heterotrimeric G Protein

Detection of phospholipase C-β 2 activation by G-protein subunits

1998 ◽  
Author(s):  
Suzanne Scarlata ◽  
Loren Runnels ◽  
Mario Rebecchi
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
Protein Subunits

scholarly journals Multi-omics analysis of glucose-mediated signaling by a moonlighting Gβ protein Asc1/RACK1

PLoS Genetics ◽  
2021 ◽  
Vol 17 (7) ◽  
pp. e1009640
Author(s):  
Shuang Li ◽  
Yuanyuan Li ◽  
Blake R. Rushing ◽  
Sarah E. Harris ◽  
Susan L. McRitchie ◽  
...  
Keyword(s):  
G Protein ◽  
Glucose Sensing ◽  
Heterotrimeric G Proteins ◽  
Glucose Addition ◽  
Protein Subunits ◽  
Individual Gene ◽  
Gene Transcripts ◽  
G Protein Coupled

Heterotrimeric G proteins were originally discovered through efforts to understand the effects of hormones, such as glucagon and epinephrine, on glucose metabolism. On the other hand, many cellular metabolites, including glucose, serve as ligands for G protein-coupled receptors. Here we investigate the consequences of glucose-mediated receptor signaling, and in particular the role of a Gα subunit Gpa2 and a non-canonical Gβ subunit, known as Asc1 in yeast and RACK1 in animals. Asc1/RACK1 is of particular interest because it has multiple, seemingly unrelated, functions in the cell. The existence of such “moonlighting” operations has complicated the determination of phenotype from genotype. Through a comparative analysis of individual gene deletion mutants, and by integrating transcriptomics and metabolomics measurements, we have determined the relative contributions of the Gα and Gβ protein subunits to glucose-initiated processes in yeast. We determined that Gpa2 is primarily involved in regulating carbohydrate metabolism while Asc1 is primarily involved in amino acid metabolism. Both proteins are involved in regulating purine metabolism. Of the two subunits, Gpa2 regulates a greater number of gene transcripts and was particularly important in determining the amplitude of response to glucose addition. We conclude that the two G protein subunits regulate distinct but complementary processes downstream of the glucose-sensing receptor, as well as processes that lead ultimately to changes in cell growth and metabolism.

scholarly journals Interplay between the heterotrimeric G-protein subunits Gαq and Gαi2 sets the threshold for chemotaxis and TCR activation

2009 ◽  
Vol 10 (1) ◽  
pp. 27 ◽  
Author(s):  
Jacob Ngai ◽  
Marit Inngjerdingen ◽  
Torunn Berge ◽  
Kjetil Taskén
Keyword(s):  
G Protein ◽  
Heterotrimeric G Protein ◽  
Protein Subunits ◽  
Tcr Activation

scholarly journals Novel bimodal effects of the G-protein tissue transglutaminase on adrenoreceptor signalling

1999 ◽  
Vol 343 (3) ◽  
pp. 541-549 ◽  
Author(s):  
Jianwen ZHANG ◽  
Janusz TUCHOLSKI ◽  
Mathieu LESORT ◽  
Richard S. JOPE ◽  
Gail V. W. JOHNSON
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
Tissue Transglutaminase ◽  
Human Neuroblastoma ◽  
Heterotrimeric G Protein ◽  
Expression Levels ◽  
Pi Hydrolysis ◽  
Low Expression

Tissue transglutaminase (tTG) is a novel G-protein that previous studies showed can couple ligand-bound activated α1B adrenoreceptors to phospholipase C-δ, resulting in phosphoinositide (PI) hydrolysis. In human neuroblastoma SH-SY5Y cells we found that although endogenous tTG can facilitate α1B adrenoreceptor-stimulated PI hydrolysis, its contribution is minor compared with the classical heterotrimeric G-protein Gq/11. Further, we show that the α1B adrenoreceptor recruits tTG to the membrane and that this recruitment is enhanced by agonist occupancy of the receptor. In addition, the effects of tTG on signalling are bimodal. At low expression levels, tTG enhanced α1B adrenoreceptor-stimulated PI hydrolysis, whereas at higher expression levels tTG attenuated significantly this response. These findings are the first to demonstrate that a protein can both facilitate and attenuate receptor-stimulated PI hydrolysis.

Sign in / Sign up

Export Citation Format

Share Document