Biochemical characterization of the three major subclasses of lipoprotein A-I preparatively isolated from human plasma.
Apolipoprotein (apo) A-I is the major protein constituent of plasma high-density lipoproteins (HDL). HDL consist of two major classes of apoA-I-containing lipoproteins: LpA-I and LpA-I:A-II. LpA-I includes heterogeneous lipoprotein particles that differ in size and hydrated density. LpA-I was isolated by immunoaffinity chromatography from the fasting plasma of 24 normal human subjects and separated by gel filtration chromatography. Three major subclasses of LpA-I were eluted: large (Lg-LpA-I), medium (Md-LpA-I), and small LpA-I (Sm-LpA-I). By nondenaturing gradient PAGE, Lg-LpA-I, Md-LpA-I, and Sm-LpA-I had mean Strokes diameters of 10.8 +/- 0.5, 8.9 +/- 0.5, and 7.5 +/- 0.3 nm, respectively. The lipid/protein ratios were 1.25 +/- 0.12 for Lg-LpA-I, 0.75 +/- 0.10 for Md-LpA-I, and 0.38 +/- 0.08 for Sm-LpA-I. Lg-LpA-I was relatively lipid and cholesteryl ester rich compared with Md-LpA-I and Sm-LpA-I. Sm-LpA-I contained phospholipids as the major lipid component. ApoA-I was the major apolipoprotein in all LpA-I subfractions, whereas apoE was present only in Lg-LpA-I and apoA-IV was associated with both Md-LpA-I and Sm-LpA-I. All three LpA-I subclasses exhibited predominantly alpha mobility on agarose electrophoresis. Lg-LpA-I migrated as a diffuse band in the fast alpha position, whereas Md-LpA-I and Sm-LpA-I migrated to the slow alpha position.(ABSTRACT TRUNCATED AT 250 WORDS)
Duverger
N
N
Molecular Disease Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Rader
D
D
Duchateau
P
P
Fruchart
J C
JC
Castro
G
G
Brewer
H B
HB
D000328:Adult; D000818:Animals; D016632:Apolipoprotein A-I / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D053480:Cholesterol Ester Transfer Proteins; D002850:Chromatography, Gel; D004587:Electrophoresis, Agar Gel; D005260:Female; D006023:Glycoproteins; D006801:Humans; D017270:Lipoprotein(a) / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry; D008297:Male; D051379:Mice; D011485:Protein Binding; D002785:Sterol O-Acyltransferase / Q000378:metabolism
D016632:Apolipoprotein A-I; C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins; D017270:Lipoprotein(a); C078260:lipoprotein A-I; D002784:Cholesterol; D002785:Sterol O-Acyltransferase