Identification and quantification of apolipoproteins in addition to apo[a] and apo B-100 in human lipoprotein[a].
The protein moiety of Lp[a] is widely believed to consist of one molecule of apo B-100 and one molecule of apo[a] per particle, linked by at least one disulfide bond. In this study we have re-examined the composition of Lp[a] to determine if other less abundant apolipoproteins might be present. Analysis of Lp[a] by sodium dodecyl sulfate-polyacrylamide electrophoresis under reducing conditions showed bands corresponding to < 200 kD but > 50 kD, 40 kD, 26 kD, 23 kD and 9 kD when stained with silver. Western immunoblot analysis of three preparations of Lp[a] revealed the presence of apoE and apoD. Enzyme-linked immunoassays were used to quantify apoA-I, apoA-II, apoC-I, apoC-II, apoC-III, apoE and apo B-100 in Lp[a] and autologous LDL isolated from three healthy males. There is a significant amount of apoA-I in the Lp[a], although the levels varied widely among the different samples. ApoE concentrations were consistent in the three Lp[a] samples and were between 22 and 26% of relative apo B-100 concentrations. Relatively minor amounts of apoA-II and no apoCs were detectable in the three Lp[a] preparations. In contrast, the autologous LDL preparations contained relatively higher amounts of apoA-I, apoA-II, apoE, apoC-I, apoC-II and apoC-III. The identity of the multiple bands corresponding to < 200 kD and > 54 kD and 9 kD is not established.
Blanco-Vaca
F
F
Department of Medicine, Baylor College of Medicine, Houston, TX.
Gaubatz
J W
JW
Bren
N
N
Kottke
B A
BA
Morrisett
J D
JD
Guevara
J
J
D000328:Adult; D053299:Apolipoprotein B-100; D001053:Apolipoproteins / Q000032:analysis* / Q000737:chemistry; D001055:Apolipoproteins B / Q000032:analysis*; D053241:Apoprotein(a); D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D017270:Lipoprotein(a) / Q000097:blood / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight
D053299:Apolipoprotein B-100; D001053:Apolipoproteins; D001055:Apolipoproteins B; D017270:Lipoprotein(a); D053241:Apoprotein(a)