Abstract
: Chronic membrane depolarization results in an increase in muscarinic acetylcholine receptor (mAChR) number in N1E‐115 neuroblastoma cells. Because the mAChR interacts with the guanine nucleotide binding regulatory (G) proteins, Gi and Go, the effect of chronic membrane depolarization on the levels of subunits of these G proteins was examined. Quantitation of G protein subunit levels was performed using affinity‐purified, monospecific antibodies in a quantitative immunoblot assay. Incubation with 50 μM veratridine (VTN), an activator of voltage‐sensitive Na+ channels, induced a 48 ± 15% increase in the level of the α subunit of Go. The effect of VTN was blocked by tetrodotoxin. On removal of VTN, the level of Goα decreased to control levels within 24 h. The levels of the α subunit of Gi and the common β subunit were not affected by VTN treatment. These results show that in N1E‐115 cells, the level of the α subunit of Go is regulated in a manner similar to the level of mAChR in response to chronic membrane depolarization.
