Photoaffinity labeling of muscle-type nicotinic acetylcholine receptors and neuronal/nicotinic alpha-bungarotoxin binding sites with a derivative of alpha-bungarotoxin
Joy, A.M.; Siegel, H.N.; Lukas, R.J.
Brain Research. Molecular Brain Research 17(1-2): 95-100
ISSN/ISBN: 0169-328X PMID: 8381915 Accession: 009189832
Neuronal/nicotinic alpha-bungarotoxin binding sites (nBgtS) found in the nervous system are not well characterized. In this study, photolabile toxin derivatives have been used in affinity labeling protocols to investigate the subunit composition of nBgtS expressed by different neuron-like cell lines. Data obtained was compared to the known subunit composition of toxin-binding muscle-type nicotinic acetylcholine receptors (nAChR). Muscle-type nAChR-rich membranes prepared from Torpedo electroplax contain components with corrected apparent molecular sizes of 41, 46, 50, 62 and 66 kDa that are reactive with toxin. The photoaffinity labeling patterns for preparations derived from cells of the TE671 clone, which express muscle-type nAChR, are very similar to that of cells of the IMR-32 or SH-SY5Y clonal lines, which express nBgtS. There is consistent labeling of four polypeptides with corrected apparent molecular weights of 40, 43, 47 and 56 kDa. These results suggest that both mammalian muscle-type nAChR and mammalian nBgtS are similarly composed of at least four kinds of subunits.