Journal of Neuroscience, Vol 10, 3460-3467, Copyright © 1990 by Society for Neuroscience
Developmental expression of the 43K and 58K postsynaptic membrane proteins and nicotinic acetylcholine receptors in Torpedo electrocytes
WJ LaRochelle, V Witzemann, W Fiedler and SC Froehner
Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03756.
The expression of the postsynaptic 43-kDa and 58-kDa proteins and actin
during development of the Torpedo marmorata electric organ was compared to
that of nicotinic acetylcholine receptors (AChRs). Western blot analysis
demonstrates that AChRs and proteins of 43 kDa (43K protein) and 58 kDa
(58K protein) are all present prior to synaptogenesis. Subsequently, levels
of all 3 synaptic proteins increase dramatically during differentiation and
innervation of electrocytes. In contrast, actin is present in relatively
high concentrations at early times and decreases thereafter. The equimolar
ratio of AChRs and the 43K protein found in the adult electric organ is
established early in development. Furthermore, the AChR and 43K protein
share a common postsynaptic localization in electrocytes following synapse
formation. Aggregates of the AChR that form at the ventral pole of the
oval-shaped electrocytes prior to innervation, however, show no detectable
immunofluorescence staining with anti-43K monoclonal antibodies. Therefore,
in some cases, aggregation of AChRs occurs without the 43K protein.
