DISTRIBUTION OF APOLIPOPROTEIN-E BETWEEN FREE AND A-II COMPLEXED FORMS IN VERY-LOW-DENSITY AND HIGH-DENSITY-LIPOPROTEINS - FUNCTIONAL IMPLICATIONS

被引:17
作者
BORGHINI, I [1 ]
JAMES, RW [1 ]
BLATTER, MC [1 ]
POMETTA, D [1 ]
机构
[1] UNIV GENEVA,HOP CANTONAL,DEPT MED,DIV DIABETOL,24 RUE MICHELI DU CREST,CH-1211 GENEVA 4,SWITZERLAND
基金
新加坡国家研究基金会;
关键词
APOLIPOPROTEIN-E; APO-E ISOFORM; APOLIPOPROTEIN-A-II; HDL; VLDL; LIPOPROTEIN METABOLISM;
D O I
10.1016/0005-2760(91)90034-F
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The stability of apolipoprotein E/lipoprotein associations has been examined as a function of apolipoprotein E phenotype. Visualisation by immunoblotting showed plasma apolipoprotein E to be present in two forms; the free form and, as previously described, an E-A-II complex. In very low density lipoproteins isolated by gel filtration from subjects with E3/3 and E4/3 phenotypes, apolipoprotein E was present essentially in the free form (ratio free: complex of 12.2 and 37.5, respectively). Exploiting ultracentrifugation as the disruptive agent, very-low-density lipoproteins thus isolated were shown to have substantially lower ratios (5.6 and 5.4, respectively) reflecting preferential loss of free apolipoprotein E. In high-density lipoproteins isolated by gel filtration from E3/3 phenotypes, apolipoprotein E was largely present as an E-A-II complex (80.3%). In contrast, the majority of apolipoprotein E in high-density lipoproteins from E4/3 phenotypes was present in the free form (58.7%). In both phenotypes, the content of free apolipoprotein E was markedly reduced by ultracentrifugation. The results confirm the notion that the formation of the E-A-II complex is a major determinant of the stability of apolipoprotein E-high-density lipoprotein associations. Moreover, that the predominant, ancestral isoform, apolipoprotein E3, exists largely as an E-A-II complex in higher density lipoproteins has important functional implications for this plasma source of apolipoprotein E.
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页码:139 / 146
页数:8
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