Journal of Neuroscience, Vol 7, 1792-1798, Copyright © 1987 by Society for Neuroscience
Immunological identification of a nicotinic acetylcholine receptor on bovine chromaffin cells
LS Higgins and DK Berg
Two probes previously shown to distinguish the nicotinic ACh receptor of
chick ciliary ganglion neurons also recognize a component on the surface of
bovine chromaffin cells in culture that displays the properties expected
for the chromaffin nicotinic ACh receptor. The first probe is a monoclonal
antibody, mAb 35, raised against ACh receptor from Electrophorus electric
organ, and the second is an alpha- neurotoxin, Bgt 3.1, purified from B.
multicinctus venom. mAb 35 binds specifically to a single class of
high-affinity sites on the chromaffin cells in culture. Scatchard analysis
indicates a KD of 2.1 +/- 0.2 nM for the binding and a Bmax of 1.6 +/- 0.1
X 10(4) mAb 35 sites per cell. The number of sites on the cells can be
reduced through modulation by exposure of the cells to Bgt 3.1. The
modulation can be blocked by the cholinergic ligands d-tubocurarine and
carbamylcholine. Long-term exposure to the agonist carbamylcholine alone
also reduces the number of mAb 35 binding sites. Bgt 3.1 inhibits
nicotine-induced catecholamine release from the cells to the same extent
and with the same concentration dependence that it modulates the number of
mAb 35 sites on the cells. In addition, mAb 35 treatment of the cells
causes a specific and almost complete blockade of nicotine-induced
catecholamine release, apparently through a modulation of the receptor.
These results indicate that the bovine chromaffin component recognized by
mAb 35 and Bgt 3.1 is likely to be the nicotinic ACh receptor on the cells
and that it has many similarities to ACh receptors on chick autonomic
neurons.