Cited by 90Cholesterol and Lipid MetabolismLipoproteins and Cardiovascular HealthLipid Membrane Structure and Behavior

Characterization of the Heparin Binding Sites in Human Apolipoprotein E

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Saito, Hiroyuki, Dhanasekaran, Padmaja, Nguyen, David, Baldwin, Faye, Weisgraber, Karl H., Wehrli, Suzanne, Phillips, Michael C., Lund-Katz, Sissel·2003·Journal of Biological Chemistry

Abstract

Apolipoprotein (apo) E mediates lipoprotein remnant clearance via interaction with cell-surface heparan sulfate proteoglycans. Both the 22-kDa N-terminal domain and 10-kDa C-terminal domain of apoE contain a heparin binding site; the N-terminal site overlaps with the low density lipoprotein receptor binding region and the C-terminal site is undefined. To understand the molecular details of the apoE-heparin interaction, we defined the microenvironments of all 12 lysine residues in intact apoE3 and examined their relative contributions to heparin binding. Nuclear magnetic resonance measurements showed that, in apoE3-dimyristoyl phosphatidylcholine discs, Lys-143 and -146 in the N-terminal domain and Lys-233 in the C-terminal domain have unusually low pK(a) values, indicating high positive electrostatic potential around these residues. Binding experiments using heparin-Sepharose gel demonstrated that the lipid-free 10-kDa fragment interacted strongly with heparin and a point mutation K233Q largely abolished the binding, indicating that Lys-233 is involved in heparin binding and that an unusually basic lysine microenvironment is critical for the interaction with heparin. With lipidated apoE3, it is confirmed that the Lys-233 site is completely masked and the N-terminal site mediates heparin binding. In addition, mutations of the two heparin binding sites in intact apoE3 demonstrated the dominant role of the N-terminal site in the heparin binding of apoE even in the lipid-free state. These results suggest that apoE interacts predominately with cell-surface heparan sulfate proteoglycans through the N-terminal binding site. However, Lys-233 may be involved in the binding of apoE to certain cell-surface sites, such as the protein core of biglycan.

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Crossref · 10.1074/jbc.m213207200

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Authors
Saito, H., Dhanasekaran, P., Nguyen, D., Baldwin, F., Weisgraber, K. H., Wehrli, S., Phillips, M. C., & Lund-Katz, S.
Affiliations
  • Children's Hospital of Philadelphia (US)
  • University of California, San Francisco (US)
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
2003-04
Volume
278
Issue
17
Pages
14782-14787
ISSN
0021-9258 (ISSN-L)
OpenAlex
W2008655430
Cited by
90
References
53
Citations by year
2026: 1 · 2025: 8 · 2024: 3 · 2023: 6 · 2022: 5 · 2021: 4 · 2020: 4 · 2019: 4 · 2018: 2 · 2017: 3 · 2016: 6 · 2015: 3 · 2014: 5 · 2013: 3 · 2012: 1
FWCI
3.20
Type
journal article
Language
en
Open access
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
National Heart, Lung, and Blood Institute (HL-41633, P01HL041633, R01HL056083, HL-56083)
Topics
  • Health Sciences › Medicine › Surgery › Cholesterol and Lipid Metabolism
  • Health Sciences › Medicine › Surgery › Lipoproteins and Cardiovascular Health
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Lipid Membrane Structure and Behavior
Keywords
apolipoprotein E, heparin binding, heparan sulfate proteoglycans, electrostatic potential, N-terminal domain, C-terminal domain, biglycan, APOE3, point mutations
MeSH terms
Apolipoproteins E, Binding Sites, Heparin, Humans, Lipids, Mutation, Phosphatidylcholines, Protein Binding, Protein Structure, Tertiary, Nuclear Magnetic Resonance, Biomolecular, Amino Acids, Basic

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