CONCENTRATION OF INTRACELLULAR HEPATIC APOLIPOPROTEIN-E IN GOLGI-APPARATUS SACCULAR DISTENSIONS AND ENDOSOMES

Citation
S. Dahan et al., CONCENTRATION OF INTRACELLULAR HEPATIC APOLIPOPROTEIN-E IN GOLGI-APPARATUS SACCULAR DISTENSIONS AND ENDOSOMES, The Journal of cell biology, 127(6), 1994, pp. 1859-1869
Citations number
65
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell Biology
Journal title
ISSN journal
0021-9525
Volume
127
Issue
6
Year of publication
1994
Part
2
Pages
1859 - 1869
Database
ISI
SICI code
0021-9525(1994)127:6<1859:COIHAI>2.0.ZU;2-1
Abstract
The intrahepatic distribution of apolipoprotein E has been assessed by immunogold labeling of cryosections as well as by Western blotting of organelles isolated from liver homogenates. Both techniques supported the prior analytical fractionation studies of Wong (1989) who conclud ed that intrahepatic apoE was largely endosomal. All endosomal compone nts decorated by gold particles indicative of apoE antigenicity in cry osections appeared filled with lipoprotein-like particles thereby acco unting for this prominent morphological feature of isolated liver endo somes. The distribution of gold particles about the hepatic Golgi appa ratus revealed a high content of apoE in closely apposed endosomes, ca . 400 nm in diameter, double labeled for apoE and internalized HRP. Re markably, apoE (but not internalized HRP) was also observed within sac cular distensions of all saccules of stacked Golgi cisternae but absen t from the flattened saccular components as was also observed for apoB . This contrasted with albumin, the major secretory protein, which was uniformly distributed throughout the hepatic Golgi apparatus. These o bservations support a growing body of evidence for intra-Golgi sorting of secretory material in hepatic Golgi apparatus. The lack of any imm unoreactive apoE or albumin in small 70-90 nm vesicles about the Golgi cisternae suggests limits to current models of vesicle-mediated intra -Golgi transport.