Characterization of the heparin binding sites in human apolipoprotein E
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.
| Medienart: |
Artikel |
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| Erscheinungsjahr: |
2003 |
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| Erschienen: |
2003 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:278 |
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| Enthalten in: |
The Journal of biological chemistry - 278(2003), 17 vom: 25. Apr., Seite 14782-7 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Saito, Hiroyuki [VerfasserIn] |
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| Themen: |
9005-49-6 |
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| Anmerkungen: |
Date Completed 16.07.2003 Date Revised 06.02.2021 published: Print-Electronic Citation Status MEDLINE |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
NLM123657695 |
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| 041 | |a eng | ||
| 100 | 1 | |a Saito, Hiroyuki |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Characterization of the heparin binding sites in human apolipoprotein E |
| 264 | 1 | |c 2003 | |
| 336 | |a Text |b txt |2 rdacontent | ||
| 337 | |a ohne Hilfsmittel zu benutzen |b n |2 rdamedia | ||
| 338 | |a Band |b nc |2 rdacarrier | ||
| 500 | |a Date Completed 16.07.2003 | ||
| 500 | |a Date Revised 06.02.2021 | ||
| 500 | |a published: Print-Electronic | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a 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 | ||
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a Research Support, U.S. Gov't, P.H.S. | |
| 650 | 7 | |a Amino Acids, Basic |2 NLM | |
| 650 | 7 | |a Apolipoproteins E |2 NLM | |
| 650 | 7 | |a Lipids |2 NLM | |
| 650 | 7 | |a Phosphatidylcholines |2 NLM | |
| 650 | 7 | |a Heparin |2 NLM | |
| 650 | 7 | |a 9005-49-6 |2 NLM | |
| 700 | 1 | |a Dhanasekaran, Padmaja |e verfasserin |4 aut | |
| 700 | 1 | |a Nguyen, David |e verfasserin |4 aut | |
| 700 | 1 | |a Baldwin, Faye |e verfasserin |4 aut | |
| 700 | 1 | |a Weisgraber, Karl H |e verfasserin |4 aut | |
| 700 | 1 | |a Wehrli, Suzanne |e verfasserin |4 aut | |
| 700 | 1 | |a Phillips, Michael C |e verfasserin |4 aut | |
| 700 | 1 | |a Lund-Katz, Sissel |e verfasserin |4 aut | |
| 773 | 0 | 8 | |i Enthalten in |t The Journal of biological chemistry |d 1945 |g 278(2003), 17 vom: 25. Apr., Seite 14782-7 |w (DE-627)NLM000004995 |x 1083-351X |7 nnns |
| 773 | 1 | 8 | |g volume:278 |g year:2003 |g number:17 |g day:25 |g month:04 |g pages:14782-7 |
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| 951 | |a AR | ||
| 952 | |d 278 |j 2003 |e 17 |b 25 |c 04 |h 14782-7 | ||