Journal of Neuroscience, Vol 13, 2424-2429, Copyright © 1993 by Society for Neuroscience
An 83 kDa O-GlcNAc-glycoprotein is found in the axoplasm and nucleus of Aplysia neurons
SP Elliot, R Schmied, CA Gabel and RT Ambron
Department of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Glycoproteins containing O-linked N-acetylglucosamine (O-GlcNAc) are
present in axons of Aplysia neurons (Gabel et al., 1989) and among
transcription factors and other proteins in the nucleus of eukaryotic cells
(Jackson and Tjian, 1988). A recently discovered pathway in neurons
transports proteins through the axon and then into the nucleus (Ambron et
al., 1992). If any of the axonal O-GlcNAc glycoproteins use this pathway,
then the axon and the nucleus will have these glycoproteins in common. We
addressed this issue by using galactosyltransferase and UDP-3H-galactose to
label and identify the glycoproteins in three regions of Aplysia neurons:
axoplasm, extruded from nerves; nuclei, isolated by manual dissection of
single neurons; and cytoplasm, obtained after removal of nuclei. At least
21 glycoproteins were labeled by this procedure; several, at 200, 180, 83,
76, and 66 kDa, from the nucleus and axoplasm comigrated after SDS- PAGE.
Radiolabeled galactosyl-N-acetylglucosaminitol was released from the
glycoproteins by base/borohydride, thereby verifying the presence of
O-GlcNAc. Comparison of the 83 kDa glycoprotein from the nucleus and
axoplasm revealed that both were soluble, had multiple O-GlcNAcs, and were
bound to WGA. Thus, the 83 kDa constituent is a good candidate to use the
axonal transport/nuclear import pathway.