This work was performed with the financial assistance of the following grants: National Heart and Lung Institute; USPHS Grant HL-06285; USPHS Training Grant HL-05725, and Bressler Research Fund, University of Maryland.
3H-fucose incorporation into glycoproteins of toad bladder epithelial cells†
Article first published online: 3 FEB 2005
Copyright © 1977 Wiley-Liss, Inc.
American Journal of Anatomy
Volume 148, Issue 1, pages 33–47, January 1977
How to Cite
Strum, J. M. and Ekblad, E. B. M. (1977), 3H-fucose incorporation into glycoproteins of toad bladder epithelial cells. Am. J. Anat., 148: 33–47. doi: 10.1002/aja.1001480104
- Issue published online: 3 FEB 2005
- Article first published online: 3 FEB 2005
- Manuscript Accepted: 13 SEP 1976
Electron microscope autoradiography was used to detect the incorporation of 3H-fucose into glycoproteins of toad bladder epithelial cells. After short exposure to 3H-fucose, without a chase period, the Golgi regions of all four cell types were labeled. When exposure to 3H-fucose was followed by chase periods (1, 3, 4 and 6 hours) the apical and basal-lateral plasma membranes of granular cells were heavily labeled. Apical granules and the cytoplasm of granular cells were also labeled, suggesting that they both provide the means for glycoprotein transfer from the Golgi to the plasma membranes. The heaviest labeling in mitochondria-rich cells, after the 1- and 3-hour chase periods, was over the apical tubules, although the apical and basal-lateral plasma membranes were also heavily labeled. After the 4- and 6-hour chases, the labeling of the apical tubules decreased, whereas the labeling of the plasma membranes increased, strongly suggesting that in these cells apical tubules play a major role in the transfer of glycoproteins from Golgi to the plasma membrane. Our results demonstrate that the route of 3H-fucose incorporation into plasma membrane glycoproteins and the rate of glycoprotein synthesis and breakdown are not the same in the two major epithelial cell types in toad bladder.