Identification and characterization of apolipoprotein(AII-E2-AII) complex in human plasma lipoprotein.
A new apolipoprotein complex designated as the apo(AII-E2-AII) complex was identified in the lipoprotein fractions of human plasma with apoE phenotypes containing apoE2 (E4/E2, E3/E2, and E2/E2). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by an immunoblotting assay using anti-apoE or anti-apoAII antibodies, established that the apo(AII-E2-AII) complex, with a molecular weight of 58,000, was identical to the complex consisting of apoE and apoAII, and that it also dissociated following reduction with beta-mercaptoethanol. This new complex was also demonstrated to be distinct from the apo(E-AII) complex and apoE monomer by isoelectric focusing, in the samples that were not treated with beta-mercaptoethanol. In apoE phenotype E3/E2, the apo(AII-E2-AII) complex was primarily included in the high-density lipoprotein (HDL, 1.063 < d < 1.21 g/ml) fraction, but was also observed in a small quantity in the very-low-density lipoprotein (VLDL, d < 1.006 g/ml) fraction. For further characterization, the apo(AII-E2-AII) complex was isolated by preparative SDS-PAGE, and no contamination of apo(E-AII) complex and apoE monomer was detected by immunoblotting assay using an anti-apoE antibody. It was confirmed by an enzyme-linked immunosorbent assay (ELISA) system that a molecular ratio between apoAII monomer and apoE in the isolated apo(AII-E2-AII) complex was approx. 2, when the apo(E-AII) complex was used as a standard with the ratio of 1:1. It indicates that the apo(AII-E2-AII) complex is formed from two molecules of apoAII monomer and one molecule of apoE.(ABSTRACT TRUNCATED AT 250 WORDS)
Tozuka
M
M
Central Clinical Laboratories, Shinshu University Hospital, Matsumoto, Japan.
Hidaka
H
H
Miyachi
M
M
Furihata
K
K
Katsuyama
T
T
Kanai
M
M
D016633:Apolipoprotein A-II / Q000032:analysis*; D053329:Apolipoprotein E2; D001057:Apolipoproteins E / Q000097:blood*; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007525:Isoelectric Focusing; D008074:Lipoproteins / Q000097:blood*; D008623:Mercaptoethanol / Q000494:pharmacology
D016633:Apolipoprotein A-II; D053329:Apolipoprotein E2; D001057:Apolipoproteins E; D008074:Lipoproteins; D008623:Mercaptoethanol; D004228:Dithionitrobenzoic Acid