Molecular Basis of Receptor/G Protein Coupling Selectivity Studied by Coexpression of Wild Type and Mutant m2 Muscarinic Receptors with Mutant GαqSubunits†

Biochemistry ◽  
1997 ◽  
Vol 36 (6) ◽  
pp. 1487-1495 ◽  
Author(s):  
Evi Kostenis ◽  
Bruce R. Conklin ◽  
Jürgen Wess
Keyword(s):  
G Protein ◽  
Muscarinic Receptors ◽  
Molecular Basis ◽  
Wild Type ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
M2 Muscarinic Receptors

Mutant M1 muscarinic receptors with increased agonist affinity and G protein coupling

Life Sciences ◽  
1999 ◽  
Vol 64 (6-7) ◽  
pp. 563
Author(s):  
W.S. Messer ◽  
X.-P. Huang ◽  
P.I. Nagy ◽  
F.E. Williams ◽  
S.M. Peseckis
Keyword(s):  
G Protein ◽  
Muscarinic Receptors ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
Agonist Affinity ◽  
M1 Muscarinic ◽  
M1 Muscarinic Receptors

scholarly journals Increased Notch 1 Expression and Attenuated Stimulatory G Protein Coupling to Adenylyl Cyclase in Osteonectin-Null Osteoblasts

Endocrinology ◽  
2007 ◽  
Vol 148 (4) ◽  
pp. 1666-1674 ◽  
Author(s):  
Catherine B. Kessler ◽  
Anne M. Delany
Keyword(s):  
Adenylyl Cyclase ◽  
G Protein ◽  
Cell Fate ◽  
Osteoblastic Cells ◽  
Matricellular Protein ◽  
Wild Type ◽  
Notch 1 ◽  
Matrix Assembly ◽  
G Protein Coupling ◽  
Protein Coupling

Osteonectin, or secreted protein acidic and rich in cysteine, is one of the most abundant noncollagen matrix components in bone. This matricellular protein regulates extracellular matrix assembly and maturation in addition to modulating cell behavior. Mice lacking osteonectin develop severe low-turnover osteopenia, and in vitro studies of osteonectin-null osteoblastic cells showed that osteonectin supports osteoblast formation, maturation, and survival. The present studies demonstrate that osteonectin-null osteoblastic cells have increased expression of Notch 1, a well-documented regulator of cell fate in multiple systems. Furthermore, osteonectin-null cells are more plastic and less committed to osteoblastic differentiation, able to pursue adipogenic differentiation given the appropriate signals. Notch 1 transcripts are down-regulated by inducers of cAMP in both wild-type and osteonectin-null osteoblasts, suggesting that the mutant osteoblasts may have a defect in generation of cAMP in response to stimuli. Indeed, many bone anabolic agents signal through increased cAMP. Wild-type and osteonectin-null osteoblasts generated comparable amounts of cAMP in response to forskolin, a direct stimulator of adenylyl cyclase. However, the ability of osteonectin-null osteoblasts to generate cAMP in response to cholera toxin, a direct stimulator of Gs, was attenuated. These data imply that osteonectin-null osteoblasts have decreased coupling of Gs to adenylyl cyclase. Because osteonectin promotes G protein coupling to an effector, our studies support the concept that low-turnover osteopenia can result from reducing G protein coupled receptor activity.

G-Protein coupling of muscarinic receptors in adult and neonatal rat submandibular cells

1996 ◽  
Vol 168 (1) ◽  
pp. 166-172 ◽  
Author(s):  
Jeanclare Seagrave ◽  
Lizabeth J. Johnson ◽  
Lee E. Goodwin ◽  
J. Ricardo Martinez
Keyword(s):  
G Protein ◽  
Muscarinic Receptors ◽  
Neonatal Rat ◽  
G Protein Coupling ◽  
Protein Coupling

Structural basis of receptor/G protein coupling selectivity studied with muscarinic receptors as model systems

Life Sciences ◽  
1997 ◽  
Vol 60 (13-14) ◽  
pp. 1007-1014 ◽  
Author(s):  
Jürgen Wess ◽  
Jie Liu ◽  
Nathalie Blin ◽  
June Yun ◽  
Christian Lerche ◽  
...  
Keyword(s):  
G Protein ◽  
Muscarinic Receptors ◽  
Model Systems ◽  
Structural Basis ◽  
G Protein Coupling ◽  
Protein Coupling

scholarly journals The role of the third intracellular loop of the neutrophil N-formyl peptide receptor in G protein coupling

1993 ◽  
Vol 294 (2) ◽  
pp. 581-587 ◽  
Author(s):  
E R Prossnitz ◽  
O Quehenberger ◽  
C G Cochrane ◽  
R D Ye
Keyword(s):  
Amino Acids ◽  
G Protein ◽  
Formyl Peptide Receptor ◽  
Wild Type ◽  
Intracellular Loop ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
The Third ◽  
Third Intracellular Loop ◽  
Formyl Peptide

The G-protein-coupled N-formyl peptide receptor (FPR) contains one of the smallest known third intracellular loops of this class of receptors, consisting of only 15 amino acids. To study the role of this region of the receptor in G protein coupling and signal transduction, we generated a deletion mutant (D3i) in which 10 amino acids of the loop were removed, as well as a series of site-directed mutants containing substitutions of the charged and polar amino acids of this loop. The D3i mutant, expressed at normal levels on the cell surface, displayed a KD for labelled N-formyl-Met-Leu-Phe ([3H]FMLP) of 165 nM. This value compares with a KD for the wild-type FPR of 1.0 nM, or 20 nM in the presence of guanosine 5′-[gamma-thio]triphosphate, which uncouples G proteins from the receptor. These results indicate that D3i contains significant structural defects, beyond the disruption of G protein coupling, that affect ligand binding properties. Ten site-directed mutants generated in the third intracellular loop (T226A, K227E, H229A, K230Q, K235Q, S236A, S236A/S237G, R238G, R241E and S244A) displayed KD values between 0.5 and 1.0 nM, with expression levels between 22% (K227E) and 111% (H229A) of that of wild type receptor. The capacity of the mutants for signal transductions was determined by measuring intracellular Ca2+ mobilization. Eight of the ten mutants displayed EC50 values for FMLP of between 0.07 and 0.9 nM, as compared with 0.12 nM for the wild-type receptor. The two mutants K227E and R238G had EC50 values of 2.7 and 2.9 nM respectively. The increase in EC50 could be accounted for partially by the low levels of receptor expression. All ten mutants gave maximum levels of Ca2+ mobilization similar to that produced by the wild-type FPR. These results contradict the conclusions reached with other G-protein-coupled receptors and indicate that the third intracellular loop of the FPR does not have a critical role in the functional coupling of G proteins.

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