scholarly journals Monoclonal antibodies against the acetylcholine receptor γ-subunit as site specific probes for receptor tyrosine phosphorylation

FEBS Letters ◽  
1995 ◽  
Vol 363 (1-2) ◽  
pp. 195-198 ◽  
Author(s):  
Socrates J. Tzartos ◽  
Elisabeth Tzartos ◽  
John S. Tzartos
Keyword(s):  
Monoclonal Antibodies ◽  
Tyrosine Phosphorylation ◽  
Acetylcholine Receptor ◽  
Site Specific ◽  
Γ Subunit

Acetylcholine receptor assembly is stimulated by phosphorylation of its γ subunit

Neuron ◽  
1991 ◽  
Vol 7 (4) ◽  
pp. 659-666 ◽  
Author(s):  
William N. Green ◽  
Anthony F. Ross ◽  
Toni Claudio
Keyword(s):  
Acetylcholine Receptor ◽  
Γ Subunit ◽  
Receptor Assembly

scholarly journals On-Resin Strategy to Label α-Conotoxins: Cy5-RgIA, a Potent α9α10 Nicotinic Acetylcholine Receptor Imaging Probe

2020 ◽  
Vol 73 (4) ◽  
pp. 327
Author(s):  
Markus Muttenthaler ◽  
Simon T. Nevin ◽  
Marco Inserra ◽  
Richard J. Lewis ◽  
David J. Adams ◽  
...  
Keyword(s):  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Resonance Energy ◽  
Peptide Sequence ◽  
Hill Coefficient ◽  
Receptor Imaging ◽  
Nicotinic Acetylcholine ◽  
Site Specific

In-solution conjugation is the most commonly used strategy to label peptides and proteins with fluorophores. However, lack of site-specific control and high costs of fluorophores are recognised limitations of this approach. Here, we established facile access to grams of Cy5-COOH via a two-step synthetic route, demonstrated that Cy5 is stable to HF treatment and therefore compatible with tert-butyloxycarbonyl solid phase peptide synthesis (Boc-SPPS), and coupled Cy5 to the N-terminus of α-conotoxin RgIA while still attached to the resin. Folding of the two-disulfide containing Cy5-RgIA benefitted from the hydrophobic nature of Cy5, resulting in only the globular disulfide bond isomer. In contrast, wild-type α-RgIA folded into the inactive ribbon and bioactive globular isomer under the same conditions. Labelled α-RgIA retained its ability to inhibit acetylcholine (100µM)-evoked current reversibly with an IC50 of 5.0nM (Hill coefficient=1.7) for Cy5-RgIA and an IC50 of 1.6 (Hill coefficient=1.2) for α-RgIA at the α9α10 nicotinic acetylcholine receptor (nAChR) heterologously expressed in Xenopus oocytes. Cy5-RgIA was then used to successfully visualise nAChRs in the RAW264.7 mouse macrophage cell line. This work introduced not only a new and valuable nAChR probe, but also a new versatile synthetic strategy that facilitates production of milligram to gram quantities of fluorophore-labelled peptides at low cost, which is often required for invivo experiments. The strategy is compatible with Boc- and 9-fluorenylmethoxycarbonyl (Fmoc)-chemistry, allows site-specific labelling of free amines anywhere in the peptide sequence, and can also be used for the introduction of Cy3/Cy5 fluorescence resonance energy transfer (FRET) pairs.

Local Anesthetics Inhibit Muscarinic Receptor-mediated Activation of Extracellular Signal-regulated Kinases in Rat Pheochromocytoma PC12 Cells 

1999 ◽  
Vol 91 (4) ◽  
pp. 1014-1014 ◽  
Author(s):  
Zhiming Tan ◽  
Shuji Dohi ◽  
Kenji Ohguchi ◽  
Shigeru Nakashima ◽  
Yoshinori Nozawa
Keyword(s):  
Tyrosine Phosphorylation ◽  
Pc12 Cells ◽  
Acetylcholine Receptor ◽  
Local Anesthetics ◽  
Muscarinic Acetylcholine Receptor ◽  
Erk Activation ◽  
Muscarinic Acetylcholine ◽  
M3 Muscarinic Acetylcholine Receptor ◽  
Extracellular Signal ◽  
Pheochromocytoma Pc12

Background Because protein phosphorylation is a key mechanism for controlling cellular functions and extracellular signal-regulated kinase (ERK) plays a role in cellular signal transduction, the authors wanted to determine whether local anesthetics interfere with biochemical signaling molecules. Methods Protein tyrosine phosphorylation and ERK activation induced by carbachol, an agonist for muscarinic acetylcholine receptors, were examined in rat pheochromocytoma PC12 cells, a model for investigating signal transduction. Carbachol-induced tyrosine-phosphorylated proteins of 44 and 42 kd were determined by Western blot analysis and identified as activated ERK1 and ERK2 using anti-ERK antibody. The ERK activation was blocked by preincubation with atropine or an M3 muscarinic acetylcholine receptor antagonist 4-diphenyacetooxy-1, 1-dimethylpiperidinium, indicating that is was mediated by M3 muscarinic acetylcholine receptor activation. Then, in the presence of local anesthetic, the carbachol-induced tyrosine phosphorylation and ERK activation were evaluated. The effects of three Na+ current-modifying reagents on carbachol-induced ERK activation were also evaluated. Results Procaine (10(-4) to 10(-3) M) inhibited carbachol-induced tyrosine phosphorylation and ERK activation in a concentration-dependent manner. Although tetracaine, lidocaine, and bupivacaine similarly suppressed carbachol-induced tyrosine phosphorylation and ERK activation, neither tetrodotoxin, veratridine, nor ouabain affected the carbachol-induced ERKs activation. Both ERKs were also activated by 4beta-phorbol 12-myristate 13-acetate, an activator of protein kinase C, and fluoroaluminate (AlF4-), respectively, but procaine did not affect ERK activation induced by these two substances. The inhibition of carbachol-induced ERK activation by procaine was not modified by a phosphatase inhibitor, calyculin A. Conclusions The current results indicate that local anesthetics inhibit the activity of the signal-transducing molecule(s) leading to M3 muscarinic acetylcholine receptor-mediated ERK activation in PC12 cells. Such action is unlikely to be a result of the drug's action on Na+ channels or on the electrochemical gradients of the neuronal cell membrane.

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