Journal of Neuroscience, Vol 10, 346-350, Copyright © 1990 by Society for Neuroscience
Synaptic localization and neural regulation of an N- acetylgalactosaminyl transferase in skeletal muscle
LJ Scott, J Balsamo, JR Sanes and J Lilien
Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110.
We have previously documented the properties of a approximately 220-kDa
cell surface glycosyltransferase that transfers N-acetylgalactosamine to
oligosaccharide chains (Balsamo et al., 1986b). Because N-
acetylgalactosamine-terminated carbohydrates are concentrated at the
neuromuscular junction (Scott et al., 1988), we assayed skeletal muscle for
the presence of the N-acetylgalactosaminyl transferase. Using
immunohistochemical methods, we found that the enzyme is localized at
neuromuscular junctions on normal adult rat muscle fibers. Biochemical
assays confirm that junctional areas are highly enriched in the
approximately 220-kDa immunoreactive species as well as in enzyme activity
associated with the approximately 220-kDa species. This restricted
distribution is dependent on synaptic integrity, as the enzyme appears
extrasynaptically on denervation. These results provide a plausible
metabolic basis for the localization of a synapse-specific carbohydrate and
demonstrate that the expression of a glycosyltransferase is regulated by
synaptic interactions.