Back to Search
Start Over
Perturbation of glycoprotein processing affects the neurotoxin-responsive Na+ channel in neuroblastoma cells.
- Source :
-
Carbohydrate research [Carbohydr Res] 1986 Jun 01; Vol. 149 (1), pp. 185-98. - Publication Year :
- 1986
-
Abstract
- The activity of neurotoxin-responsive Na+ channels in mouse neuroblastoma cells, N-18, was examined after treating the cells with compounds that are reported to perturb intracellular traffic. The compounds used have been shown to either alter glycoprotein synthesis and processing, (swainsonine, castanospermine, monensin, and retinoic acid) or receptor mediated endocytosis (mevinolin, 7-ketocholesterol, and chloroquine), or both. All of these compounds inhibited the activity of the neurotoxin-responsive Na+ channel with the exception of retinoic acid which increased the activity. Na+ channel activity was measured by two methods: (a) In vivo, the efflux of 86Rb was measured by use of the cells in monolayer culture, and (b) in vitro, the flux of 86Rb was measured from artificial phospholipid vesicles containing the partially purified Na+ channel. In both cases, 86Rb flux responded to stimulating neurotoxins, veratridine and scorpion venom, and was inhibited by tetrodotoxin as characteristic of excitable membranes. One of the perturbing compounds, swainsonine, was examined in detail. Treatment of N-18 cells with 10 microM swainsonine for 24 h markedly reduced the activity of the neurotoxin-responsive Na+ channel, as shown by the neurotoxin-stimulated efflux of 86Rb in vivo. In addition, after reconstitution into phospholipid vesicles of the partially purified Na+ channel from swainsonine-treated cells, reduced 86Rb flux was observed when compared with that of nontreated cells. Furthermore, the activity was not recovered in other less purified fractions. A comparison of the glycopeptides from the treated and nontreated cells by size, charge, and lectin-binding affinities was consistent with the formation of hybrid oligosaccharides after swainsonine treatment. It is concluded that the oligosaccharide residues of the Na+ channel glycoprotein must be processed to the mature complex-type for full activity. The stimulation of channel activity by treatment with retinoic acid supported this conclusion.
- Subjects :
- Animals
Cell Line
Ion Channels drug effects
Kinetics
Mice
Protein Processing, Post-Translational
Rubidium metabolism
Scorpion Venoms pharmacology
Tetrodotoxin pharmacology
Tretinoin pharmacology
Tritium
Veratridine pharmacology
Glycoproteins biosynthesis
Ion Channels metabolism
Neuroblastoma metabolism
Neurotoxins pharmacology
Sodium metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0008-6215
- Volume :
- 149
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Carbohydrate research
- Publication Type :
- Academic Journal
- Accession number :
- 2425966
- Full Text :
- https://doi.org/10.1016/s0008-6215(00)90377-x