S-Prenylated Cysteine Analogs Inhibit Receptor-Mediated G Protein Activation in Native Human Granulocyte and Reconstituted Bovine Retinal Rod Outer Segment Membranes

Biochemistry ◽  
1995 ◽  
Vol 34 (15) ◽  
pp. 4952-4961 ◽  
Author(s):  
Alexander Scheer ◽  
Peter Gierschik
Keyword(s):  
G Protein ◽  
Outer Segment ◽  
Protein Activation ◽  
Rod Outer Segment ◽  
Retinal Rod ◽  
G Protein Activation

Opioid-Activated Postsynaptic, Inward Rectifying Potassium Currents in Whole Cell Recordings in Substantia Gelatinosa Neurons

1998 ◽  
Vol 80 (6) ◽  
pp. 2954-2962 ◽  
Author(s):  
S. P. Schneider ◽  
W. A. Eckert ◽  
A. R. Light
Keyword(s):  
Membrane Potential ◽  
G Protein ◽  
Potassium Currents ◽  
Substantia Gelatinosa ◽  
Opioid Agonist ◽  
Membrane Hyperpolarization ◽  
Whole Cell ◽  
Protein Activation ◽  
G Protein Activation ◽  
Whole Cell Recordings

Schneider, S. P., W. A. Eckert III, and A. R. Light. Opioid-activated postsynaptic, inward rectifying potassium currents in whole cell recordings in substantia gelatinosa neurons. J. Neurophysiol. 80: 2954–2962, 1998. Using tight-seal, whole cell recordings from isolated transverse slices of hamster and rat spinal cord, we investigated the effects of the μ-opioid agonist (d-Ala2, N-Me-Phe4,Gly5-ol)-enkephalin (DAMGO) on the membrane potential and conductance of substantia gelatinosa (SG) neurons. We observed that bath application of 1–5 μM DAMGO caused a robust and repeatable hyperpolarization in membrane potential ( V m) and decrease in neuronal input resistance ( R N) in 60% (27/45) of hamster neurons and 39% (9/23) of rat neurons, but significantly only when ATP (2 mM) and guanosine 5′-triphosphate (GTP; 100 μM) were included in the patch pipette internal solution. An ED50 of 50 nM was observed for the hyperpolarization in rat SG neurons. Because G-protein mediation of opioid effects has been shown in other systems, we tested if the nucleotide requirement for opioid hyperpolarization in SG neurons was due to G-protein activation. GTP was replaced with the nonhydrolyzable GTP analogue guanosine-5′- O-(3-thiotriphosphate) (GTP-γ-S; 100 μM), which enabled DAMGO to activate a nonreversible membrane hyperpolarization. Further, intracellular application of guanosine-5′- O-(2-thiodiphosphate) (GDP-β-S; 500 μM), which blocks G-protein activation, abolished the effects of DAMGO. We conclude that spinal SG neurons are particularly susceptible to dialysis of GTP by whole cell recording techniques. Moreover, the depletion of GTP leads to the inactivation of G-proteins that mediate μ-opioid activation of an inward-rectifying, potassium conductance in these neurons. These results explain the discrepancy between the opioid-activated hyperpolarization in SG neurons observed in previous sharp electrode experiments and the more recent failures to observe these effects with whole cell patch techniques.

scholarly journals β-Amyloid Peptide-induced Apoptosis Regulated by a Novel Protein Containing a G Protein Activation Module

2001 ◽  
Vol 276 (22) ◽  
pp. 18748-18756 ◽  
Author(s):  
Eileen M. Kajkowski ◽  
C. Frederick Lo ◽  
Xiaoping Ning ◽  
Stephen Walker ◽  
Heidi J. Sofia ◽  
...  
Keyword(s):  
G Protein ◽  
Amyloid Peptide ◽  
Protein Activation ◽  
G Protein Activation ◽  
Β Amyloid ◽  
Β Amyloid Peptide ◽  
Induced Apoptosis ◽  
Novel Protein
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