Journal of Neuroscience, Vol 10, 3255-3262, Copyright © 1990 by Society for Neuroscience
Cyclic AMP-dependent phosphorylation of a neuronal acetylcholine receptor alpha-type subunit
S Vijayaraghavan, HA Schmid, SW Halvorsen and DK Berg
Department of Biology, University of California, San Diego, La Jolla 92093.
Chick ciliary ganglion neurons have nicotinic acetylcholine receptors
(AChRs) that mediate synaptic transmission through the ganglion. A cAMP-
dependent process has previously been shown to enhance the ACh response of
the neurons 2- to 3-fold without requiring the synthesis of new receptors.
We show here that the receptors can be phosphorylated in situ by a
cAMP-dependent process. The phosphorylation occurs predominantly on
components of 50 and 58 kDa. Both derive from putative ligand-binding alpha
3 subunits, with the smaller phosphorylated species probably representing a
degradation product of the larger. The increase in receptor phosphorylation
caused by incubating the neurons with a cAMP analog parallels the increase
observed in the ACh response, with respect to both time course and relative
extent. The phosphorylation of ciliary ganglion AChRs differs from that
reported for electric organ AChRs, which occurs primarily on the
non-ligand- binding gamma and delta subunits and increases the rate of
agonist- induced receptor desensitization.