A Targeted, Differential Top-Down Proteomic Methodology for Comparison of ApoA-I Proteoforms in Individuals with High and Low HDL Efflux Capacity

Henrique Dos Santos Seckler, Luca Fornelli, R. Kannan Mutharasan, C. Shad Thaxton, Ryan Fellers, Martha Daviglus, Allan Sniderman, Daniel Rader, Neil L. Kelleher, Donald M. Lloyd-Jones, Philip D. Compton, John T. Wilkins*

*Corresponding author for this work

Research output: Contribution to journalArticle

12 Scopus citations


Top-down proteomics (TDP) allows precise determination/characterization of the different proteoforms derived from the expression of a single gene. In this study, we targeted apolipoprotein A-I (ApoA-I), a mediator of high-density-lipoprotein cholesterol efflux (HDL-E), which is inversely associated with coronary heart disease risk. Absolute ApoA-I concentration and allelic variation only partially explain interindividual HDL-E variation. Therefore, we hypothesize that differences in HDL-E are associated with the abundances of different ApoA-I proteoforms. Here, we present a targeted TDP methodology to characterize ApoA-I proteoforms in serum samples and compare their abundances between individuals. We characterized 18 ApoA-I proteoforms using selected-ion monitoring coupled to electron-transfer dissociation mass spectrometry. We then compared the abundances of these proteoforms between two groups of four participants, representing the individuals with highest and lowest HDL-E values within the Chicago Healthy Aging Study (n = 420). Six proteoforms showed significantly (p < 0.0005) higher intensity in high HDL-E individuals: canonical ApoA-I [fold difference (fd) = 1.17], carboxymethylated ApoA-I (fd = 1.24) and, with highest difference, four fatty acylated forms: palmitoylated (fd = 2.16), oleoylated (fd = 2.08), arachidonoylated (fd = 2.31) and one bearing two modifications: palmitoylation and truncation (fd = 2.13). These results demonstrate translational potential for targeted TDP in revealing, with high sensitivity, associations between interindividual proteoform variation and physiological differences underlying disease risk.

Original languageEnglish (US)
Pages (from-to)2156-2164
Number of pages9
JournalJournal of Proteome Research
Issue number6
StatePublished - Jun 1 2018



  • ApoA-I
  • HDL efflux
  • acylations
  • apolipoproteins
  • atherosclerosis
  • cholesterol
  • palmitoylation
  • proteoforms
  • top-down proteomics

ASJC Scopus subject areas

  • Biochemistry
  • Chemistry(all)

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