Electrophysiological evidence shows that voltage-dependent calcium channel (VDCC) activity can be regulated by a large number of neurotransmitters. In particular, guanine nucleotide binding regulatory protein (G protein)-mediated inhibitory modulation of the channel activity has been deduced from evidence that GTP analogues and purified G proteins are able to mimic this effect. The G proteins involved are pertussis toxin (PTx) sensitive. The purpose of the present study was to investigate, using biochemical techniques, whether G protein activation modulates the recognition site for omega-conotoxin GVIA (CgTx), a peptide neurotoxin that selectively labels a population of high-threshold VDCC. Undifferentiated and differentiated (1 mM dibutyryl cyclic AMP, 4 days) NG 108-15 cells were used. In both crude cellular extracts specific binding of 125I-CgTx was characterized. Differentiation induced a sixfold increase in the number of binding sites and doubled the KD value. The in vitro addition of guanylylimidodiphosphate (GMP-PNP; a nonhydrolyzable analogue of GTP) to extracts prepared from differentiated cells reduced the 125I-CgTx binding by 48%. This effect, observed in undifferentiated cells as well, was also caused by other triphosphate guanine nucleotides, such as GTP, but not by guanosine 5'-O-(2-thiodiphosphate) or adenine nucleotides. Treatment of the cells with PTx prevented the GMP-PNP effect. Moreover, the results obtained after preincubation with specific antisera raised against the alpha subunits of Gi1-2 and Go suggest that Go is the G protein responsible for the observed effect.

Bergamaschi, S., Govoni, S., Battaini, F.m., Trabucchi, M.m., Del Monaco, S., Parenti, M. (1992). G protein modulation of omega-conotoxin binding sites in neuroblastoma x glioma NG 108-15 hybrid cells. JOURNAL OF NEUROCHEMISTRY, 59(2), 536-543.

G protein modulation of omega-conotoxin binding sites in neuroblastoma x glioma NG 108-15 hybrid cells

BATTAINI, FIORENZO MARIA;TRABUCCHI, MARCO MARIO;
1992-08-01

Abstract

Electrophysiological evidence shows that voltage-dependent calcium channel (VDCC) activity can be regulated by a large number of neurotransmitters. In particular, guanine nucleotide binding regulatory protein (G protein)-mediated inhibitory modulation of the channel activity has been deduced from evidence that GTP analogues and purified G proteins are able to mimic this effect. The G proteins involved are pertussis toxin (PTx) sensitive. The purpose of the present study was to investigate, using biochemical techniques, whether G protein activation modulates the recognition site for omega-conotoxin GVIA (CgTx), a peptide neurotoxin that selectively labels a population of high-threshold VDCC. Undifferentiated and differentiated (1 mM dibutyryl cyclic AMP, 4 days) NG 108-15 cells were used. In both crude cellular extracts specific binding of 125I-CgTx was characterized. Differentiation induced a sixfold increase in the number of binding sites and doubled the KD value. The in vitro addition of guanylylimidodiphosphate (GMP-PNP; a nonhydrolyzable analogue of GTP) to extracts prepared from differentiated cells reduced the 125I-CgTx binding by 48%. This effect, observed in undifferentiated cells as well, was also caused by other triphosphate guanine nucleotides, such as GTP, but not by guanosine 5'-O-(2-thiodiphosphate) or adenine nucleotides. Treatment of the cells with PTx prevented the GMP-PNP effect. Moreover, the results obtained after preincubation with specific antisera raised against the alpha subunits of Gi1-2 and Go suggest that Go is the G protein responsible for the observed effect.
ago-1992
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/14 - FARMACOLOGIA
English
Con Impact Factor ISI
Virulence Factors, Bordetella; Iodine Radioisotopes; Precipitin Tests; Calcium Channels; Guanylyl Imidodiphosphate; Immunoblotting; Brain Neoplasms; omega-Conotoxin GVIA; Animals; Glioma; Binding Sites; Neuroblastoma; Receptors, Neurotransmitter; Tumor Cells, Cultured; Hybrid Cells; Peptides, Cyclic; GTP-Binding Proteins; Pertussis Toxin; Protein Binding
Bergamaschi, S., Govoni, S., Battaini, F.m., Trabucchi, M.m., Del Monaco, S., Parenti, M. (1992). G protein modulation of omega-conotoxin binding sites in neuroblastoma x glioma NG 108-15 hybrid cells. JOURNAL OF NEUROCHEMISTRY, 59(2), 536-543.
Bergamaschi, S; Govoni, S; Battaini, Fm; Trabucchi, Mm; Del Monaco, S; Parenti, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/51567
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