Radioimmunoassay of human arginine-rich apolipoprotein, apoprotein E. Concentration in blood plasma and lipoproteins as affected by apoprotein E-3 deficiency.
A radioimmunoassay for apolipoprotein E in human blood serum has been developed that measures equally the major polymorphic species of the protein (apolipoproteins E-1, E-2, E-3, and E-4) and the apo E in the dimer of apolipoproteins E and A-II. The assay is specific and yields values for apolipoprotein E in very low density lipoproteins that agree closely with those obtained by a quantitative electrophoretic method. Apolipoprotein E is also present in at least one species of high density lipoprotein, but the content of apolipoprotein E in the lipoprotein fractions of plasma is uncertain owing to dissociation during ultracentrifugation. The concentration of apolipoprotein E is higher in serum of normolipidemic, premenopausal women than in men of comparable age and is a direct function of the serum triglyceride level. Apolipoprotein E levels are increased out of proportion to triglyceride levels in hyperlipidemic patients with familial dysbetalipoproteinemia (homozygotes for lack of apolipoprotein E-3). Heterozygous relatives of homozygotes have significantly higher apolipoprotein E levels in serum than unaffected relatives. The concentration of partially degraded (remnant) triglyceride-rich lipoproteins also appears to be increased in heterozygotes, who comprise about 15% of the population.
D000596:Amino Acids / Q000032:analysis; D000918:Antibody Specificity; D001053:Apolipoproteins / Q000032:analysis* / Q000097:blood / Q000172:deficiency; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D006995:Hypobetalipoproteinemias / Q000097:blood* / Q000235:genetics; D007009:Hypolipoproteinemias / Q000097:blood*; D011863:Radioimmunoassay; D014280:Triglycerides / Q000097:blood
D000596:Amino Acids; D001053:Apolipoproteins; D014280:Triglycerides