Referenced in: none

Automatically associated channels: Kv2.1

Title: Neuronal alpha-bungarotoxin receptors differ structurally from other nicotinic acetylcholine receptors.

Authors: F Rangwala, R C Drisdel, S Rakhilin, E Ko, P Atluri, A B Harkins, A P Fox, S S Salman, W N Green

Journal, date & volume: J. Neurosci., 1997 Nov 1 , 17, 8201-12

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/9334396

Abstract
We have characterized the alpha-bungarotoxin receptors (BgtRs) found on the cell surface of undifferentiated pheochromocytoma (PC12) cells. The PC12 cells express a homogeneous population of alpha7-containing receptors that bind alpha-Bgt with high affinity (Kd = 94 pM). The BgtRs mediate most of the response elicited by nicotine, because the BgtR-specific antagonists methyllycaconitine and alpha-Bgt block approximately 90% of the whole-cell current. The binding of nicotinic agonists to cell-surface BgtRs was highly cooperative with four different agonists showing Hill coefficients in the range of 2.3-2.4. A similar agonist binding cooperativity was observed for BgtR homomers formed from chimeric alpha7/5HT3 subunits expressed in tsA 201 cells. Two classes of agonist binding sites, in the ratio of 4:1 for PC12 cell BgtRs and 3:1 for alpha7/5HT3 BgtRs, were revealed by bromoacetylcholine alkylation of the reduced sites on both PC12 BgtRs and alpha7/5HT3 BgtRs. We conclude from this data that PC12 BgtRs and alpha7/5HT3 homomers contain at least three distinguishable agonist binding sites and thus are different from other nicotinic receptors.