Domain Swapping Reveals That Low Density Lipoprotein (LDL) Type A Repeat Order Affects Ligand Binding to the LDL Receptor
The low density lipoprotein receptor (LDLR) plays a key role in plasma cholesterol homeostasis by binding and internalizing lipoprotein ligands. Studies have revealed that one or more of the seven LDL type A repeats (LA1–LA7) in the receptor are responsible for apolipoprotein binding. In the present...
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Published in | The Journal of biological chemistry Vol. 284; no. 20; pp. 13396 - 13400 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
15.05.2009
American Society for Biochemistry and Molecular Biology |
Subjects | |
Online Access | Get full text |
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Summary: | The low density lipoprotein receptor (LDLR) plays a key role in plasma cholesterol homeostasis by binding and internalizing lipoprotein ligands. Studies have revealed that one or more of the seven LDL type A repeats (LA1–LA7) in the receptor are responsible for apolipoprotein binding. In the present study, protein engineering was performed to swap or replace key LA repeats in a recombinant soluble LDLR (sLDLR). Although wild type sLDLR showed strong ligand binding activity, an sLDLR variant in which LA repeat 5 was replaced by a second copy of LA repeat 2 showed low binding activity. Likewise, a variant wherein LA repeats 2 and 5 were swapped displayed low binding activity. At the same time, substitution of LA repeat 2 with a second a copy of repeat 5 resulted in a receptor with ligand binding activity similar to wild type LDLR. When binding assays were conducted with human low density lipoprotein as ligand, LA repeat order was a less important determinant of binding activity. Taken together, the data indicate that the sequential order of LA repeats plays a key role in ligand binding properties of LDLR. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Recipient of a California Tobacco Related Disease Research Program New Investigator Award (17KT-0026). To whom correspondence should be addressed: Center for the Prevention of Obesity, Cardiovascular Disease and Diabetes, Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609. Tel.: 510-450-7645; E-mail: rryan@chori.org. This work was supported, in whole or in part, by National Institutes of Health Grant HL 64159 (to R. O. R.). |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M900194200 |