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An electron microscope autoradiographic study of the carbohydrate recognition systems in rat liver. II. Intracellular fates of the 125I-ligands.
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MedLine Citation:
PMID:  511942     Owner:  NLM     Status:  MEDLINE    
Electron microscope autoradiographic and biochemical methods were used to study the intracellular fates of several 125I-glycoproteins, known to be specifically bound and internalized by the different cell types in the liver. At the earliest times examined (1--2 min), 125I-glycoproteins (ASGP) were localized predominantly along the sinusoidal front of hepatocytes. Analysis of the distribution of autoradiographic grains indicated that: (a) approximately 40--60% of the 125I-ligand could be ascribed to the plasmalemma; (b) a significant fraction had already been internalized; yet (c) very little 125I-ligand was present in the lysosome-Golgi region. Between 4 and 15 min after administration of 125I-ASGPs, there was a dramatic redistribution of autoradiographic grains from regions of the plasmalemma and peripheral cytoplasm (30% decrease) to the lysosome-Golgi region (30% increase). At longer times (30 min), there was continued drainage of 125I-ASGP into this region. The grain density over secondary lysosomes was 60--90 times higher than that over recognizable Golgi elements, clearly indicating that lysosomes were the ultimate destination of the 125I-ASGP. However, no more than 60% of the total 125I-ligand could be localized to lysosome-rich regions of the hepatocyte, with the remaining 40% primarily in the intermediate cytoplasm. Biochemical evidence for proteolysis of the internalized 125I-ASGP (presumably within lysosomes) was obtained when [125I]-mono-iodotyrosine was found in the liver (i.e., hepatocytes) at times later than 15 min. The temporal redistribution observed for mannose and N-acetylglucosamine-terminated glycoproteins (ahexosamino-orosomucoid and agalacto-orosomucoid, respectively) in endothelial cells indicated that the 125I-ligands resided in macropinocytic vesicles (1--15 min) before their ultimate residence in dense bodies (15 min). The same 125I-ligands were also localized to structures resembling secondary lysosomes in Kupffer cells. The lysosomal nature of "these organelles" was implied from the appearance of [125I]mono-iodotyrosine in the liver at later times. 125I-beta-glucuronidase followed the same intracellular pathway in both cell types but was not degraded.
A L Hubbard; H Stukenbrok
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of cell biology     Volume:  83     ISSN:  0021-9525     ISO Abbreviation:  J. Cell Biol.     Publication Date:  1979 Oct 
Date Detail:
Created Date:  1980-02-26     Completed Date:  1980-02-26     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0375356     Medline TA:  J Cell Biol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  65-81     Citation Subset:  IM    
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MeSH Terms
Glycoproteins / metabolism*
Golgi Apparatus / metabolism
Iodine Radioisotopes
Kupffer Cells / ultrastructure
Liver / metabolism*,  ultrastructure
Lysosomes / metabolism
Microscopy, Electron
Reg. No./Substance:
0/Glycoproteins; 0/Iodine Radioisotopes

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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Journal Information
Journal ID (nlm-ta): J Cell Biol
ISSN: 0021-9525
ISSN: 1540-8140
Publisher: The Rockefeller University Press
Article Information
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Print publication date: Day: 1 Month: 10 Year: 1979
Volume: 83 Issue: 1
First Page: 65 Last Page: 81
ID: 2110433
Publisher Id: 80072254
PubMed Id: 511942

An electron microscope autoradiographic study of the carbohydrate recognition systems in rat liver. II. Intracellular fates of the 125I- ligands

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