Location of Glycoproteins That Contain Glucosamine in Plant Tissues

When radioactive d-glucosamine is provided to Acer pseudoplatanus cells in liquid culture in order to label those glycoproteins that contain amino sugars, it is incorporated predominantly into a crude cell wall fraction. This observation was confirmed histologically by preparing autoradiographs of thin tissue sections from plasmolyzed cells. Highly purified cell wall material from unlabeled cells has also been shown to contain small amounts of glucosamine. Similarly, about one-half of the amino sugar recovered from cultured cells of Nicotiana tabacum is present in their cell walls. In corn roots, however, the labeled glycoproteins that are formed after glucosamine incorporation are predominantly cytoplasmic and not deposited outside the protoplast.