Isolation of axonally transported glycoproteins with goldfish visual system myelin

[3H]fucose labeled glycoproteins which are rapidly transported in the goldfish optic nerve have been isolated with purified preparations of goldfish optic tectal myelin. SDS acrylamide gels of myelin proteins isolated one day after intraocular injection of fucose show a broad distribution of radioactivity among high molecular weight proteins. At progressively longer times after injection there is a shift in the distribution of radioactivity with the buildup of a peak of label with electrophoretic mobility corresponding to a molecular weight of approximately 50,000. There is no corresponding peak of radioactivity in gels of total tectal membranes. Gels of myelin labeled through intracranial injections of fucose also show no single prominent peak of radioactivity. Results are discussed with reference to possible mechanisms for the shift in radioactivity patterns on gels and the possible functional significance of the myelin-associated glycoproteins.