Characterization of Axonally Transported Glycoproteins in Regenerating Garfish Olfactory Nerve

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Abstract
Changes in composition and concanavalin A (Con A) binding of axonally transported glycoproteins and their pronase-generated glycopeptides in regenerating garfish olfactory nerve were studied. A previous study had demonstrated a regeneration-related increase in the proportion of [3H]glucosamine label in lower-MW Con A-binding glycopeptides derived from transported glycoproteins. Further analysis of carbohydrate composition shows that these molecules resemble mannose-rich oligosaccharides in composition and are increased in absolute amount in regenerating nerve. Subcellular analysis shows that the Con A-binding glycopeptides are enriched in membrane subfractions, particularly in a high-density fraction that morphologically resembles isolated cell surface coat. Regeneration-related changes in intact axonally transported glycoproteins were also detected. Sodium dodecyl sulfate gel electrophoresis of transport-labeled glycoproteins disclosed growth-correlated increases in radioactivity associated with 180-200 K [kiloDalton], 105-115 K, and 80-90 K components, while a 150-160 K MW class of glycoproteins was diminished in relative labeling. Intact glycoproteins displaying an affinity for Con A were also augmented in regenerating nerve, the increase occurring primarily in molecules in the 50-140 K range.