Journal of Lipid Research, Vol 29, 981-995, Copyright © 1988 by Lipid Research, Inc.
Apolipoproteins of the orotic acid fatty liver: implications for the biogenesis of plasma lipoproteins
R Hay, R Fleming, W O'Connell, J Kirschner and W Oppliger
Department of Pathology, University of Chicago, IL 60637.
Rats fed orotic acid develop fatty livers characterized by triglyceride-
laden, membrane-bounded vesicles designated "liposomes." We have measured
the levels of apolipoproteins in isolated liposomes and other subcellular
fractions by SDS-polyacrylamide gel electrophoresis, electrotransfer, and
immunodecoration. Apolipoproteins Bh, Bl, E, and C appear to cofractionate;
for these proteins, the liposomal pool represents a large portion of their
total intracellular mass. However, liposomes are deficient in both variants
of apoB relative to apoE and apoC when compared with rat plasma very low
density lipoprotein (VLDL). Albumin and apolipoproteins A-I and A-IV are
also found in liposomes, but this organelle represents a minor fraction of
their total intracellular mass. The liposomal apolipoproteins show varying
degrees of association with cisternal lipid and with organelle membranes.
Orotic acid may selectively block VLDL production at the level of particle
assembly or transorganellar movement. We conclude that liposomal contents
probably represent exaggerated accumulations of VLDL assembly
intermediates, and that the intracellular partitioning of high density
lipoprotein-destined from VLDL-destined components occurs at an early stage
in particle biogenesis. Moreover, some unique structural feature of apoB
may effect movement of VLDL assembly intermediates through secretory
organelles.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
