In vitro metabolism of apolipoprotein E

Ardon Rubinstein, Joyce Corey Gibson, Henry N. Ginsberg, W. Virgil Brown

Research output: Contribution to journalArticlepeer-review

Abstract

Apolipoprotein E plays a major role in the uptake of chylomicrons and of very-low-density lipoprotein (VLDL) remnants by the liver. It has also been clearly demonstrated that apolipoprotein E rapidly and spontaneously exchanges between lipoproteins. To assess whether all lipoprotein-bound apolipoprotein E is available to participate in spontaneous transfer and/or exchange, the present study followed the fate of radiolabeled apolipoprotein E in an in vitro system. The results show that in vitro, apolipoprotein E can be considered as having both a spontaneously exchangeable pool and a nonexchangeable pool. Based upon specific radioactivity data, only a limited amount of apolipoprotein E originating in VLDL or in high-density lipoproteins (HDL) was capable of in vitro exchange with that in other lipoprotein fractions. Lipolysis of VLDL triacylglycerol by milk lipoprotein lipase, however, resulted in complete transfer of VLDL apolipoprotein E mass and radioactivity to HDL, supporting the potential for transformation of exchangeable apolipoprotein to a transferable pool in vivo. The results of these studies indicate that during the course of lipoprotein metabolism, conformational changes occur which alter the accessibility of apolipoprotein E. Such dynamic heterogeneity may have implications for the regulation of lipoprotein metabolism.

Original languageEnglish
Pages (from-to)355-361
Number of pages7
JournalBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volume879
Issue number3
DOIs
StatePublished - 5 Dec 1986
Externally publishedYes

Keywords

  • Apolipoprotein E
  • Lipoprotein lipase
  • Lipoprotein metabolism

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