Journal of Lipid Research, Vol 27, 1035-1043, Copyright © 1986 by Lipid Research, Inc.
Identification and characterization of rat serum lipoprotein subclasses. Isolation by chromatography on agarose columns and sequential immunoprecipitation
GM Dallinga-Thie, VL Schneijderberg and A van Tol
Lipoproteins, present in serum of chow-fed rats, were fractionated
according to size by chromatography of serum on 6% agarose columns. The
distributions of apolipoprotein (apo) A-I, E, and A-IV within the high
density lipoprotein (HDL) size range (i.e., lipoprotein complexes smaller
than low density lipoproteins) showed the existence of lipoprotein
subclasses with different size and chemical composition. Sequential
immunoprecipitations were performed on these fractions obtained by agarose
column chromatography, using specific antisera against apoA-I, apoE, and
apoA-IV. The resulting precipitates and supernatants were analyzed for
cholesteryl esters, unesterified cholesterol, phospholipids, triglycerides,
and specific lipoproteins. The following conclusions were drawn from these
experiments. Sixty- three +/- 3% of apoE in the total HDL size range is
present on a large particle (mol wt 750,000). This lipoprotein contains
apoE as its sole protein constituent and is called LpE. Thirty-nine +/- 4%
of the cholesterol found in the HDL size range is present in this fraction.
The cholesterol:phospholipid ratio is 1:1.1. Sixty-nine +/- 8% of apoA- I
in the total HDL size range is present on a smaller particle (mol wt
250,000). This apoA-I-HDL has apoA-I as its major protein component and
possibly contains minor amounts of C apoproteins and A-II, but neither apoE
nor apoA-IV. It contains 39 +/- 8% of the total cholesterol found in the
HDL size range and the cholesterol:phospholipid ratio is 1:1.6.(ABSTRACT
TRUNCATED AT 250 WORDS)
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