An electron microscope autoradiographic study of the carbohydrate recognition systems in rat liver. I. Distribution of 125I-ligands among the liver cell types

A. L. Hubbard, G. Wilson, G. Ashwell, H. Stukenbrok

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Abstract

Electron microscope autoradiography was used to study the cellular localization of seven glycoproteins rapidly cleared from the circulating plasma of rats and taken up by the liver. 1 and 15 min after intravenous administration of the 125I-glycoproteins, livers were fixed in situ by perfusion and processes for autoradiography. Autoradiographic grains in the developed section were found to represent the intact 125I-ligand. A quantitative analysis of the distribution and concentration (density) of autoradiographic grains over the three major cell types of the liver was then performed. Three molecules, asialo-fetuin, asialo-orosomucoid, and lactosaminated RNase A dimer, the oligosaccharide chains of which terminate in galactose residues, were bound and internalized almost exclusively (>90%) by hepatocytes. Conversely, four molecules, the oligosaccharide chains of which terminate in either N-acetyl-glucosamine (agalacto-orosomucoid) or mannose (ahexosamino-orosomucoid, preputial β-glucuronidase, and mannobiosaminated RNase A dimer), were specifically bound and internalized by cells lining the blood sinusoids-that is, by Kupffer cells and endothelial cells. Endothelial cells were two to six times more active (on a cell volume basis) than were Kupffer cells in the internalization of these four 125I-ligands. Mannose and N-acetylglucosamine-terminated glycoproteins competed with each other for uptake into either endothelial cells or Kupffer cells, indicating that a single system recognized mannose or N-acetyl-glucosamine residues. Finally, agalacto-orosomucoid and ahexosamino-orosomucoid were also associated with hepatocytes, but competition experiments utilizing excess asialo-orosomucoid demonstrated that residual galactosyl residues were responsible for this association.

Original languageEnglish (US)
Pages (from-to)47-64
Number of pages18
JournalJournal of Cell Biology
Volume83
Issue number1
DOIs
StatePublished - 1979
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology

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